I installed a vBulletin modification that ads classified ad functionality to the forum. In order to place an ad you must purchase credits using paypal. The script seems to function and completed the paypal payment but when you return to the merchant the credits are not increased and the forum generates two errors that are PM's to the user who purchased the credits.
Links are available via PM.
I have attached the file where the coding problem is.
UNLESS YOU ARE FAMILIAR WITH VBULLETIN PLEASE DON'T WASTE YOUR TIME.