Hello, I just installed this plugin onto my site. I have Vantage already installed on the site. It seemed to have installed just fine. I keyed in the API ID, transaction key, and MD5 hash value. When I test it in a customer ID, it does not work. I receive this error message on the screen:
Fatal error: Call to undefined function mhash() in /home/tl/public_html/wp
-content/plugins/authorize-net/an-gateway.php on line 111
I spoke with someone at Authorize.net, they suggested removing the MD5 hash value, but the error message persists. Not sure how to fix this - any help would be greatly appreciated!