**Exhibit 99.1
**SIXTH AMENDMENTDated as of May 27, 2008toAMENDED AND RESTATEDRECEIVABLES SALE AGREEMENTDated as of July 20, 2004**

This Sixth Amendment (the “Amendment”), dated as of May 27, 2008, is enteredinto among IPL Funding Corporation (the “Seller”), Windmill Funding Corporation,a Delaware corporation (“Windmill”), the Liquidity Provider listed on thesignature page hereof (the “Liquidity Provider”) and ABN AMRO Bank N.V., asagent for Windmill and the Liquidity Provider (the “Agent”). 

Reference is hereby made to that certain Amended and Restated ReceivablesSale Agreement, dated as of July 20, 2004 (as amended, supplemented or otherwisemodified through the date hereof, the “Sale Agreement”), among the Seller,Windmill, the Liquidity Provider and the Agent.  Terms used herein and nototherwise defined herein which are defined in the Sale Agreement or the otherTransaction Documents (as defined in the Sale Agreement) shall have the samemeaning herein as defined therein. 

For good and valuable consideration, the receipt and adequacy of which arehereby acknowledged, the parties hereto hereby agree as follows: 

Section 1. Upon execution by the parties hereto in the space provided forthat purpose below the Sale Agreement shall be, and it hereby is, amended asfollows: 

(a) The following new defined terms are hereby added to Schedule I ofthe Sale Agreement in the appropriate alphabetical order: 

“Credit Sales” means, for any period of determination, the aggregate amountof trade receivables with credit terms of any kind originated by the  Originatorduring such period. 

“Dilution” means, for any Discount Period, the amount of Deemed Collectionsdeemed to be received during such Discount Period pursuant to Section 1.5(b). 

“Dilution Ratio” means, for any Discount Period, a fraction (expressed as apercentage), the numerator of which is the total amount of Dilutions during suchDiscount Period, and the denominator of which is the amount of Credit Salesgenerated during the most recently completed calendar month. 

“Dilution Reserve Percentage” means 2%. 

“Loss Reserve Percentage ” means 15%. 

(b) The defined term “Reserve Percentage” in Schedule I of the Sale Agreementis hereby amended in its entirety and as so amended shall read as follows: 

“Reserve Percentage” means, the sum of the Dilution Reserve Percentage andLoss Reserve Percentage. 

(c) The date “May 27, 2008” appearing in clause (d) of the defined term“Liquidity Termination Date” appearing in Schedule I of the Sale Agreement ishereby deleted and replaced with the date “May 26, 2009.” 

(d) Clause (f) of the defined term “Termination Event” is hereby amended inits entirety and as so amended shall read as follows: 

(f) the average Dilution Ratio for any three consecutive Discount Periodsexceeds 2%, the Delinquency Ratio exceeds 5%, the Default Ratio exceeds 3% orthe Loss-to Liquidation Ratio at the end of any calendar month measured for thethree month period then ending exceeds 1%; or 

Section 2. The Sale Agreement, as amended and supplemented hereby or ascontemplated herein, and all rights and powers created thereby and thereunder orunder the other Transaction Documents and all other documents executed inconnection therewith, are in all respects ratified and confirmed.  From andafter the date hereof, the Sale Agreement shall be amended and supplemented asherein provided, and, except as so amended and supplemented, the Sale Agreement,each of the other Transaction Documents and all other documents executed inconnection therewith shall remain in full force and effect. 

Section 3. This Amendment may be executed in two or more counterparts, eachof which shall constitute an original but both or all of which, when takentogether, shall constitute but one instrument. 

Section 4. This Amendment shall be governed and construed in accordance withthe internal laws of the State of Illinois. 

In Witness Whereof, the parties have caused this Amendment to be executed anddelivered by their duly authorized officers as of the date first above written. 

ABN AMRO Bank N.V., as the Agent and as the Liquidity Provider

By:____________________________________ Title:___________________________________ 

By:____________________________________ Title:___________________________________ 

Windmill Funding Corporation 

By:____________________________________ Title:___________________________________ 

IPL Funding Corporation 

By:____________________________________ Title:  Treasurer and Assistant Secretary________**