The FMLA generally prohibits an employer from taking retaliatory actions when you return to work after a period of unpaid FMLA leave.  However, the employer is not required to reinstate you in exactly the same position that you occupied prior to the leave, in recognition of the fact that the employer may have had to hire someone to fill your role during the leave period.  Because of this, the employer is only required to provide you with an equivalent position when you return—which does not have to be exactly the same as the position you occupied prior to FMLA leave, and may not even have to be paid at the same rate.