I have been accepting V/MC/AMEX/D credit cards using a different shopping cart, so I know i'm set up to take them.

I have my Zen-Cart configured to take all 4 cards. I'm using the Secure Pay module.

When customers enter an AmEx account number, they are getting an error:
The Credit Card Number does not match the Credit Card Type.

I try my own AmEx and by golly I get the same message!

Where is this verification done, and how can I change it so that AmEx is recognized as AmEx?

V/M/D all work just fine....
??

Thanks.