I'm trying to get Zen Cart ready to go live for the first time and have tried posting a payment through the Authorize.net SIM module.

I tried with an actual credit card from the shopping cart checkout, and it bounces back to the Payment Information screen with the message "There has been an error processing your credit card. Please try again."

When I log into Authorize.net, however, it says the payment has actually gone through. And an email receipt goes to me indicating that it went through.

I was getting the same errors before taking it out of test mode, and thought it was related to being in test mode, so I turned off test mode, but that made no difference.

This is different from other threads I've found on the forum, as the payment goes through but the message to the user is that it has not.

PHP v5.4.29
MySQL 5.5.37-log

What should I be looking for?

Thanks.