I am running Drupal 7.18. I have an installation of ubercart and it was working fine. I had it working with the test gateway credit card and I was able to complete purchases.
But now when I tested it today again I had a problem - when you click submit on the review order page (to finish checkout) it brings you back to the billing information page! I have installed modules and changed settings since my last time I did a submit (I don't remember when it was) but i never messed with any ubercart code.
What would be the source for this problem? I need to find the answer fast.