I am trying to checkout with SagePay. I have followed the document "Using Protx as your eCart Payment Gateway" and everything has worked fine until the actual testing. On the Confirm page, when I click submit, I am not redirected to a VSP Server. The page refreshes and any shipping or billing information disappears. There are no errors.
I am trying to understand protx since I've never set a cart up using it. I am assuming all credit card information is done on their secured site. Now, where does my M_ID and M_Key come into play? I would have thought the checkout wizard would have asked for it, but it didn't. How does SagePay know the request is coming from me?