Paid Subscription: Authorize.net - No Respose

[casDotster]

Hello,

Here is the problem I am running into. I am attempting to implement the paid subscription into vBulletin using Authorize.net.

Case 1: When I don't set the MD5 Hash value in Paid Subscriptions > Payment API > Authorize.net, I get to the generic Authorize.net billing form, and then it returns the following error: "hash check failed". The transaction shows up in the vBulletin transaction log as failed.

Case 2: I set a coresponding MD5 Hash value in both the Payment API and the Authorize.net control panel (which is limited to 20-digits). I once again get to the generic Authorize.net billing form, and then it returns the following error:
"An error occurred while trying to report this transaction to the merchant. An e-mail has been sent to the merchant informing them of the error. The following is the result of the attempt to charge your credit card.

This transaction has been approved.
It is advisable for you to contact the merchant to verify that you will receive the product or service."

When I check the Transaction Log, no information for that transaction shows up (it doesn't even show up as failed like the Hash Check Error did). It times-out trying to respond back to the vBulletin site.

Question: Does anyone know where I could find the code that calls the Authorize.net server from vBulletin. I would like to run a test to see what variables are being passed over, and I need to replace the address (ex: https://secure.authorize.net/) with a development address that Authorize.net provided me with that should echo all passed values.