Returning from external payment gateway

I'm on ZenCart v1.3.9h.

I'm trying to integrate a payment gateway (NBePay), but the code they've given me to integrate into ZenCart seems rather broken on the return call from the gateway after making payment.

So, I tell the payment gateway to return to:

http://[some website].com/test/index.php?main_page=checkout_process&zenid=70ba543232a1448424f5b74ad1272714

I included the zenid field, but when the payment gateway makes this callback, I get a timed out page:

http://[some website].com/test/index.php?main_page=time_out&zenid=70ba543232a1448424f5b74ad1272714

I confirm that this session key is in the "sessions" DB table sesskey field.

What needs to be done to get the session to resume after the return from the payment gateway?

Oh nvm. :) I found the problem. I used a different website address alias in the return URL. :doh: