For the testing of the recordset you can substitute real values for the default or runtime values. This should return a set of results for you to examine. You will need to ensure that these recordsets are working correctly in order for the other parts to do their job. When you see the link on your checkout success page does it have a value for the prod id? You should be using the id from the recordset and not the cart.
I have opened a ticket for you on this so we can exchange some more info and files. To update your ticket please login to WebAssist.com and visit your support history. Please post back with this info and the other requested info and pages.