HELP! transactions are successful, but no payment is made

I have a cart that someone else configured for me so I'm sorry for not providing any obviously needed information.
Supposedly it's set up to work with my processor who is secure pay. When making a purchase, credit card information is entered and when submitted the thank you page, order number, and order confirmation email are given. The problem is that I don't get the money! :)

The order shows as pending on the administration page and the amount is not deducted from the purchaser's credit card. It's as though the processor does not know about the transaction. Secure pay said they don't see any transactions on their end and that their system was working fine on their end.

What do I need to do to start looking??

Thanks!!!