I figured I would share my experience. I spent maybe 45 min trying to figure out why my credit cards wouldn't go through. Then I decided to look through my Authorize.net account and noticed that under unsettled transactions there was transaction status of General Error (Request rejected by FDC omaha - Invalid merchant number). The checkout process made it seem that it was the card when all along authorize.net didn't enter my merchant account number in correctly. SOO with a quick call, my account was all set