I also heard that another reason could be that they are trying to run it as a debit instead of a credit, and somehow that causes the rejection. Not sure how all of that works but recently someone told me they had a similar problem with Paxum and that turned out to be the problem.
He said if they ask debit or credit always say credit. Only use it as a debit card when at the ATM to get cash with your pin #.
Hopefully that helps you too
