[calorie]

There is one more line at the bottom of the payment_gateway.php file:

if ($apiobj->display_feedback AND !empty($apiobj->error))

Where you could change it to the following if you want:

if (($apiobj->display_feedback OR $apiobj_display_feedback) AND !empty($apiobj->error))

But a user only winds up there if the payment doesn't verify.

If you are testing in demo mode, set up a 0.01 subscription and try it live. Also, double check that all the file edits are in the correct locations. After a verified payment, you should wind up back on the payments.php page or the login thereto.