We have zencart v 1.5.4 upgraded from 1.3.9. We did the official upgrade procedure.
Only modules installed are Payment > authorize.net SIM, check/money order,
Shipping > storepickup, ups
Order total > discount coupon, group discount, gift certificates, low order fee, shipping, tax, total.

This cart has been online and was using authorize.net module for years with no issues. At some point in March the module stopped sending orders to our zencart. This may have been caused by an expired account with the company that ran our credit card transactions. Authorize.net for some reason decided it was best to set up a new account with them (not sure why they did not want to just update the existing account).

Since then we cannot get the SIM module to work. We set up via zencart instructions, and get the error: The following errors have occurred.

(14) The referrer, relay response or receipt link URL is invalid.

If we use what little information that authorize.net gives you about setting this up we instead end up with the shopper going to checkout, sends them to authorize.net site they enter in CC info and then are just looped back to the checkout page on our site. Authorize has the transaction information, but nothing is sent back to the cart.

We have relay response set to
http://ourdomainname.com/folder/inde...eckout_process

Obviously the domain name is set to our actual domain name and the name of the directory that the cart is installed in.

Any help or suggestions on this would be greatly appreciated. We have been through all FAQs on Authorize.net site as well as the forums here and still cannot get this to work. We have contacted Authorize.net repeatedly, but they are far less than helpful, the support staff is useless and blames it on zencart.

Tried using PayPal payment module and it worked fine, but would like to get this one to work as it used to. Thank you in advance for your time and help.