Credit card setup problem

I am using PC Charge Pro & NOVA credit card processing company. Ccredit card approval works fine on PC Charge pro program but i have problem intergrating it to MRMS. I have setup as describe in help for MRMS. In Tender Type I have type in "Credit Card". Now, When i try to charge credit card it comes up with errors "user not found" on approval window. Any help greatly appreciated. As i already take over business for two week and still have to use terminal to do credit cards. Vinay Patel