Turn on debug logging in the Linkpoint payment module, and review the logs to see what *is* happening correctly. And review the error logs to determine what's breaking.


One very telling approach is to do a fresh clean install of an *uncustomized* Zen Cart, then enable the payment module that you say is failing, and do a test transaction with a dummy product. See that it does indeed work properly. THEN when you see that the transaction can indeed work correctly with uncustomized code, begin narrowing your investigation with emphasis on the alterations you've made to the code, since that's where the problem exists.