Aaron-
I would need the error message to be able to better troubleshoot this issue.
As far different payment types you will just need to add multiple payment gateways under Customize > My Account > Payment Gateways.
If you wanted it to show Visa, Mastercard and AmEx, you would create 3 payment gates with the Payment Gateway Name reflecting the card type so in this case Visa, Mastercard and AmEx. This will make it so that those 3 show up in the payment type drop down. You can use the same connection ticket for all 3.
-Michael