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                                                                    EXHIBIT 10.1

                                                 Re:      Lakeview Office Center
                                                 14500 South Outer Forty Road
                                                 Chesterfield, Missouri

                            FIRST AMENDMENT TO LEASE

THE STATE OF MISSOURI         Section
                              Section        KNOW ALL MEN BY THESE PRESENTS:
COUNTY OF ST. LOUIS           Section


         THIS FIRST AMENDMENT TO LEASE (this "Amendment") has been executed as
of the 25th day of March, 2004, by Olympia Properties, L.L.C., a Washington
limited liability company, ("Landlord"), and DALEEN SOLUTIONS, INC., a Delaware
corporation ("Tenant").

                                R E C I T A L S:

         A. Landlord and Intertech Management Group, Inc. ("Prior Tenant") have
heretofore executed that certain Lease (the "Lease"), dated as of September 16,
1999, pursuant to which Tenant leased approximately 19,981 rentable square feet
of which 17,095 rentable square feet are located on the third (3rd) floor and
2,886 rentable square feet are located on the second (2nd) floor (the "Original
Premises") of that certain building known as Lakeview Office Center, 14500 South
Outer Forty Road, Chesterfield, Missouri, and more particularly described in the
Lease (the "Building"). Unless otherwise defined herein, all initially
capitalized terms will have the respective meanings ascribed thereto in the
Lease.

         B. Tenant and Vestal Corporation ("Subtenant") entered into a Sublease
Agreement ("Sublease"), dated October 1, 2002, for approximately 2,886 rentable
square feet on the second (2nd) floor of the Building, as Consented to by
Landlord pursuant to that certain Consent to Sublease, dated as of September 30,
2002, by and between Landlord, Tenant and Subtenant.

         C. Prior Tenant assigned all of its right, title and interest in the
Lease to Tenant pursuant to that certain Assignment of Lease, dated as of
December 20, 2002, by and between Tenant and Prior Tenant, as consented to by
Landlord pursuant to that certain Consent to Assignment, dated as of December
20, 2002. Tenant has assumed and accepted all of Prior Tenant's interest and
obligations under the Lease.

FIRST AMENDMENT TO LEASE          Page 1 of 6

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         D. Landlord and Tenant desire to execute this Amendment in order to
evidence their agreement to (i) reduce the size of the Original Premises, (ii)
extend the Term of the Lease and (iii) make certain other amendments to the
Lease, all as more particularly set forth in this Amendment.

         NOW THEREFORE, in consideration of the foregoing and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, Landlord and Tenant agree as follows:

                                    Article I

                               CERTAIN AMENDMENTS

         SECTION 1.01. Reduction of Premises. As of October 1, 2004 (the
"Effective Date"), the Original Premises shall be reduced by the second (2nd)
floor space containing approximately 2,886 rentable square feet in the Building
which is outlined on the floor plan attached hereto as Exhibit A (the "Give-Back
Premises") (the Original Premises, after such reduction, being the "Premises").
As of the Effective Date, the Premises shall be redefined to contain
approximately 17,095 rentable square feet on the third (3rd) floor of the
Building. As of the Effective Date, Tenant's Proportionate Share shall be
amended to 20.16% (i.e., 17,095 rentable square feet in the Premises divided by
84,193 rentable square feet in the Building). Since the expiration date of the
Sublease is November 30, 2004, Tenant shall be solely responsible for
terminating the Sublease and/or, at Landlord's sole election, arranging a direct
transaction between the Subtenant and Landlord. In connection therewith, Tenant
shall indemnify and hold Landlord harmless from and against any and all claims,
losses or causes of action asserted or alleged by Subtenant resulting from a
termination of the Lease as to the Give-Back Premises.

         SECTION 1.02. Surrender of Give-Back Premises. As of the Effective
Date, Tenant shall (and Tenant shall have caused Subtenant to) have vacated and
abandoned the Give-Back Premises and removed all office equipment, supplies and
furniture and other property, alterations, improvements, wiring and cabling as
directed by Landlord or as required under the Lease. As of the Effective Date,
Tenant shall deliver the Give-Back Premises to Landlord in broom-clean condition
and shall have no further right to the Give-Back Premises or possession of the
Give-Back Premises (i.e., Landlord may re-lease the Give-Back Premises to
another occupant and commence improvements). If Tenant fails to deliver the
Give-Back Premises in the condition required under this Section 1.02 on the
Effective Date, Tenant shall be deemed for all purposes to be in hold-over, in
addition to all other remedies available to Landlord at law or in equity.

FIRST AMENDMENT TO LEASE           Page 2 of 6

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         SECTION 1.03. Term of Lease. As of the date hereof, the Term of the
Lease shall be extended from November 30, 2004, through and including October
31, 2009, subject to adjustment and earlier termination as provided in the
Lease. Except as set forth on Exhibit C attached hereto, any and all Tenant
options to extend the Term of the Lease are hereby deleted.

         SECTION 1.04. Basic Rental/Reduction Premises. As of March 1, 2004, the
Basic Rental due and payable by Tenant to Landlord during the Term, as hereby
extended, will be as follows:

<TABLE>
<CAPTION>
                            Annual Basic Rental
     Period:                Rate per Square Foot       Monthly Basic Rental:
     -------                --------------------       ---------------------
<S>                         <C>                        <C>
 3/1/04 -  9/4/04                $12.00*                  $19,981.00*
10/1/04 -  2/28/05               $12.00                   $17,095.00
 3/1/05 -  2/28/06               $17.00                   $24,217.92
 3/1/06 -  2/28/07               $17.25                   $24,574.06
 3/1/07 -  2/29/08               $17.75                   $25,286.35
 3/1/08 -  2/28/09               $18.00                   $25,642.50
 3/1/09 - 10/31/09               $18.50                   $26,354.79
</TABLE>

* Landlord hereby abates two (2) months (April 2004 and May 2004) of Basic
Rental described above, and Tenant acknowledges that said $12.00 rate effective
through February 28, 2005, reflects a reduction in the market rent equal to
$5.00 per rentable square foot in the Premises (i.e., the market rate for the
Premises is $17.00 per rentable square foot per annum). Further, Landlord will
issue a credit for any Basic Rental already paid by Tenant at the previous rate
for March 2004. Tenant shall pay all other obligations accruing during such
months. If Tenant defaults under this Lease beyond any applicable period of
notice and cure, any remaining rent abatement or rent reduction shall cease from
the date of such default, and Tenant shall immediately pay to Landlord all sums
previously abated and/or reduced hereunder.

The Basic Rental under the Lease shall be due and payable in equal monthly
installments, each such monthly installment due and payable on the first day of
each calendar month, in advance, without demand and without setoff or deduction
whatsoever.

         SECTION 1.05. Base Year. As of March 1, 2004, the Base Year shall be
amended to be the calendar year 2004. Tenant shall continue to pay direct
electrical charges for all separately metered usage, including, without
limitation, the computer room.

         SECTION 1.06. Commissions. Landlord and Tenant acknowledge that no
brokers have been involved in this Amendment other than Sansone Group/DDR L.L.C.
and Colliers Turley Martin Tucker (collectively, "Brokers"), and Landlord will
be solely responsible for the commissions, if any, owed such Brokers by separate
agreement. Landlord and Tenant hereby

FIRST AMENDMENT TO LEASE          Page 3 of 6

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indemnify each other from the payment of any commissions owed to any broker with
respect to this Amendment resulting from the acts of such party, but not
otherwise.

         SECTION 1.07. "AS-IS." Tenant accepts the Premises "AS-IS" and Landlord
has no obligation to make, or pay or otherwise reimburse Tenant for, any
improvements, alterations or additions to the Premises, except as set forth on
Exhibit B.

         SECTION 1.08. Parking. Exhibit C of the Lease is deleted and replaced
with the following: "During the Term, as hereby extended through and including
October 31, 2009, Tenant shall be permitted to use sixty-eight (68) vehicular
parking spaces in the surface parking lot associated with the Building (the
"Parking Facility"), of which seven (7) shall be designated reserved for
Tenant's use, at no charge, subject to adjustment by Landlord upon prior notice
to Tenant. If Tenant sublets any portion of the Premises or assigns any of its
interest in this Lease, then the parking spaces allocated to Tenant hereunder
shall be reduced to the extent the ratio between the rentable square feet of the
Premises and the parking spaces granted to Tenant hereunder exceeds the Building
standard ratio of parking space per rentable square foot as established by
Landlord from time to time. Subject to the foregoing, Tenant's use of such
spaces remains subject to such terms, conditions and regulations as are from
time to time charged or applicable to patrons of the Parking Facility.

         SECTION 1.09. Extension Option. Landlord hereby grants to Tenant an
extension option subject to Exhibit C attached hereto.

         SECTION 1.10. Further Amendments. The Lease shall be and hereby is
further amended wherever necessary, even though not specifically referred to
herein, in order to give effect to the terms of this Amendment. Exhibits E and G
attached to the Lease shall be deleted and deemed null and void for all
purposes. The words "sufficient to pay all rental obligations under the Lease"
in Section 10.d. of the Lease are hereby defined to mean a "tangible net worth
equal to or greater than $8,000,000."

                                   Article II

                                  MISCELLANEOUS

         SECTION 2.01. Ratification. The Lease, as amended hereby, is hereby
ratified, confirmed and deemed in full force and effect in accordance with its
terms. Tenant represents to Landlord that Tenant (a) is currently unaware of any
default by Landlord under the Lease; and (b) has full power and authority to
execute and deliver this Amendment and this Amendment represents a valid and
binding obligation of Tenant enforceable in accordance with its terms.

         SECTION 2.02. Notices. All notices to be delivered to Landlord under
the Lease or otherwise with respect to the Premises shall, unless Landlord
otherwise notifies Tenant, be

FIRST AMENDMENT TO LEASE          Page 4 of 6

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delivered to Landlord in accordance with notice provisions of the Lease at the
management office in the Building with a copy at the same time to the following
address:

                           c/o TA Associates Realty
                           28 State Street, 10th Floor
                           Boston, Massachusetts  02109
                           Attn.: Asset Manager

All notices to be delivered to Tenant under the Lease or otherwise with respect
to the Premises shall, unless Tenant otherwise notifies Landlord, be delivered
to Tenant in accordance with notice provisions of the Lease to the Premises with
a copy at the same time to the following address:

                           c/o Daleen Technologies, Inc.
                           Attention Legal Department
                           902 Clint Moore Road, Suite 230
                           Boca Raton, Florida 33487

         SECTION 2.03. Governing Law. This Amendment shall be governed by and
construed in accordance with the laws of the State of Missouri.

         SECTION 2.04. Counterparts. This Amendment may be executed in multiple
counterparts each of which is deemed an original but together constitute one and
the same instrument. This Amendment may be executed by facsimile and each party
has the right to rely upon a facsimile counterpart of this Amendment signed by
the other party to the same extent as if such party had received an original
counterpart.

         SECTION 2.05. Landlord's Liability/Default. Any liability of Landlord
under the Lease and/or with respect to the Building, the common areas, the
Premises or otherwise shall be limited solely to its interest in the Building,
and in no event shall any personal liability be asserted against Landlord and/or
its partners, officers, directors, agents or employees in connection with the
Lease nor shall any recourse be had to any other property or assets of Landlord
or such other parties. Landlord shall not be in default hereunder and Tenant
shall not have any remedy or cause of action unless Landlord fails to perform
any of its obligations hereunder within thirty (30) days after written notice
from Tenant specifying such failure (unless such performance will, due to the
nature of the obligation, require a period of time in excess of thirty (30)
days, then after such period of time as is reasonably necessary). All
obligations of Landlord hereunder shall be construed as covenants and not
conditions; and all such obligations will be binding upon Landlord only during
the period of its ownership of the Premises and not thereafter.

         IN WITNESS WHEREOF, this Amendment has been executed as of the date and
year first above written.

FIRST AMENDMENT TO LEASE          Page 5 of 6

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Dated: April 2, 2004               LANDLORD:
                                   --------

                                   OLYMPIA PROPERTIES, L.L.C.,
                                   a Washington limited liability company

                                   By: Bartwood, L.L.C.,
                                       a Massachusetts limited liability
                                       company, Managing Member

                                       By: Realty Associates Advisors LLC,
                                           a Delaware limited liability company,
                                           Manager

                                           By: Realty Associates Advisors
                                               Trust, a Massachusetts
                                               business trust, sole member

                                               By: /s/ James P. Knowles
                                                   -----------------------------
                                                             (Officer)
                                                          Regional Director

Date: March 22, 2004               TENANT:
                                   ------

                                   DALEEN SOLUTIONS, INC.,
                                   a Delaware corporation

                                   By: /s/ William H. McCausland
                                       ------------------------------
                                   Name: William H. McCausland
                                   Title: Senior Vice President - Operations

FIRST AMENDMENT TO LEASE          Page 6 of 6

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                                    EXHIBIT A

                               GIVE-BACK PREMISES

                                 DRAWING OMMITED

                             EXHIBIT A - Page 1 of 1

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                                    EXHIBIT B

                          TENANT FINISH-WORK: ALLOWANCE

         1. Except as set forth on this Exhibit, Tenant accepts the Premises
"AS-IS" and acknowledges that Landlord has no obligation to make or otherwise
pay for any improvements, alterations or repairs thereto.

         2. Landlord will have prepared the Working Drawings for the Premises.
Tenant will review and approve the Working Drawings within five (5) business
days following receipt thereof. As used herein, "Working Drawings" shall mean
the final working drawings approved by Landlord, as amended from time to time by
any approved changes thereto, and "Work" shall mean all improvements to be
constructed in accordance with and as indicated on the Working Drawings.
Approval by Landlord of the Working Drawings shall not be a representation or
warranty of Landlord that such drawings are adequate for any use, purpose, or
condition, or that such drawings comply with any applicable law or code, but
shall merely be the consent of Landlord to the performance of the Work. Tenant
shall, at Landlord's request, sign the Working Drawings to evidence its review
and approval thereof. All changes in the Work must receive the prior written
approval of Landlord, whose approval shall not be unreasonably withheld or
delayed; provided, however, Landlord may withhold its consent in its sole and
absolute discretion if such alteration, physical addition or improvement affects
any mechanical systems or structural portions of the Premises or the Building,
and in the event of any such approved change Tenant shall, upon completion of
the Work, furnish Landlord with an accurate, reproducible "as-built" plan (e.g.,
sepia) of the improvements as constructed, which plan shall be incorporated into
this Lease by this reference for all purposes.

         3. Landlord shall obtain competitive bids from no less than three
general contractors who have been mutually agreed upon by Landlord and Tenant.
Landlord will cause the Work to be performed by contractors and subcontractors
approved in writing by Landlord.

         4. Tenant shall bear the entire cost of performing the Work (including,
without limitation, space planning and construction document fees, design of the
Work and preparation of the Working Drawings, costs of construction labor and
materials, electrical usage during construction, additional janitorial services,
approved signage, related taxes and insurance costs, all of which costs are
herein collectively called the "Total Construction Costs") in excess of the
Construction Allowance (hereinafter defined). Upon approval of the Working
Drawings and selection of a contractor, Tenant shall promptly (a) execute a work
order agreement prepared by Landlord and approved by Tenant which identifies
such drawings, itemizes the Total Construction Costs and sets forth the
Construction Allowance, and (b) pay to Landlord 50% of the amount by which the
estimated Total Construction Costs exceed the Construction Allowance. Tenant
shall pay to Landlord, within 10 days after Landlord's delivery to Tenant of an
appropriate invoice, an amount equal to the Total Construction Costs (as
adjusted for any approved changes to the Work), less (i) the amount of the
payments already made by Tenant, (ii) the amount of the

                             EXHIBIT B - Page 1 of 2

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Construction Allowance, and (iii) the cost reasonably estimated by Landlord for
completing all "punch list" items; finally, upon completion of the punch list
items, Tenant shall pay to Landlord the costs incurred in completing the same.

         5. Landlord shall provide to Tenant a construction allowance (the
"Construction Allowance") equal to the lesser of (a) $20.00 per rentable square
foot in the Premises, as reduced by the Give-Back Premises (i.e., 17,095
rentable square feet), or (b) the Total Construction Costs, as adjusted for any
approved changes to the Work; however, if Tenant or its agent is managing the
performance of the Work, then Tenant shall not become entitled to full credit
for the Construction Allowance and Landlord shall withhold from the Construction
Allowance the equivalent of ten percent (10%) of the Total Construction Costs
until thirty (30) days have passed since the Work has been substantially
completed and Tenant has caused to be delivered to Landlord (i) a list of all
contractors, subcontractors and suppliers that performed the Work on or for the
Premises, (ii) all invoices from contractors, subcontractors, and suppliers
evidencing the cost of performing the Work, together with lien waivers from such
parties, and a consent of the surety to the finished Work (if applicable), (iii)
a certificate of occupancy from the appropriate governmental authority, if
applicable to the Work, or evidence of governmental inspection and approval of
the Work and (iv) an affidavit signed by Tenant stating that all of the bills
associated with the Total Construction Costs have been paid. Any unspent portion
of the Construction Allowance remaining as of October 1, 2004, shall be credited
against Tenant's next accruing payments of Basic Rental under the Lease.

         6. Landlord or its affiliate shall supervise the Work, make
disbursements required to be made to the contractor, and act as a liaison
between the contractor and Tenant and coordinate the relationship between the
Work, the Building, and the Building's systems.

         7. To the extent not inconsistent with this Exhibit, the Lease shall
govern the performance of the Work and the Landlord's and Tenant's respective
rights and obligations regarding the improvements installed pursuant thereto.

                             EXHIBIT B - Page 2 of 2

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                                    EXHIBIT C

                                EXTENSION OPTION

         1. Provided no Event of Default exists at the time of such election,
Tenant may renew this Lease for one (1) additional period of five (5) years on
the same terms provided in this Lease (except as set forth below), by delivering
written notice of ("Tenant's Notice") the exercise thereof to Landlord not later
than eleven (11) months prior to the end of the Term. On or before the
commencement date of the extended Term, Landlord and Tenant shall execute an
amendment to this Lease extending the Term on the same terms provided in this
Lease, except as follows:

         (a) The Basic Rental payable for each month during each such extended
Term shall be the prevailing rental rate in the Building and other comparable
buildings in the metropolitan area in which the Building is located, at the
commencement of such extended Term, for space of equivalent quality, size,
utility and location, with the length of the extended Term and the credit
standing of Tenant to be taken into account;

         (b) Tenant shall have no further renewal options unless expressly
granted by Landlord in writing; and

         (c) Landlord shall lease to Tenant the Premises in their then-current
condition, and Landlord shall not provide to Tenant any allowances (e.g., moving
allowance, construction allowance, and the like) or other tenant inducements.

         2. Within thirty (30) days following delivery of Tenant's Notice,
Landlord shall deliver to Tenant a written notice ("Landlord's Notice")
specifying the Basic Rental rate per rentable square foot per annum for the
applicable additional term. Tenant shall have thirty (30) days following
delivery of Landlord's Notice to notify Landlord in writing ("Tenant's Renewal
Notice") of (i) Tenant's exercise of its right to renew the Lease at the Basic
Rental rate proposed by Landlord, or (ii) deliver to Landlord Tenant's
determination of the Basic Rental rate per rentable square foot per annum for
the applicable additional term. Upon Landlord's receipt of Tenant's
determination of the Basic Rental, both parties shall have the right for a
period of thirty (30) days to negotiate the Basic Rental rate for the additional
Term. If within ten (10) days following the expiration of the thirty (30) day
period following Tenant's submittal of its determination of the Basic Rental the
parties cannot agree for any or no reason (i.e., Landlord shall have no
liability to Tenant for failing to negotiate), then Tenant may, as its sole and
exclusive remedy, either (i) elect to accept Landlord's determination of the
Basic Rental or (ii) elect not to exercise its right to renew the Lease.
Tenant's failure to timely deliver Tenant's Renewal Notice shall be deemed
acceptance by Tenant of the Basic Rental rate proposed by Landlord.

         3. Tenant's rights under this Exhibit shall terminate if (i) this Lease
or Tenant's right to possession of the Premises is terminated, (ii) Tenant
assigns any of its interest in this Lease or

                             EXHIBIT C - Page 1 of 1

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sublets any portion of the Premises, or (iii) Tenant fails to timely exercise
its option under this Exhibit, time being of the essence with respect to
Tenant's exercise thereof.

                            EXHIBIT C - Page 2 of 1