Intuit Hosted PayPage callback extension not working with OpenCart 2.0
I have Opencart 2.0.1.1 and set up an extension that uses Intuit Hosted PayPage, but when it sends the information back to me, I just get a while screen I contacted the extension developer and he thinks everything looks like it should work. Is there something I don't know? I tried it again with a store from scratch (thought maybe I had broken something in my store) and same problem so I am at a loss for what else to try.