cash incoming payment error

hi experts!

we're integrating a front office system to SAP, we've successfully integrated AR Invoice, Check Incoming Payment and Credit Card Incoming Payment. But when it came to Cash Incoming Payment, we were unsuccessful. Another prob is, there's no error message to give us at least an idea on what's causing the error. It just won't work.

Has anyone encountered the same scenario? Can you give us any clue please on what might be causing our problem?

thanks & regards,

tessa