Try using your credit card via the Paypal option if you are having problems.
If you are having problems paying using our credit card merchant, you could try to see if your credit card works via Paypal. You do not need a Paypal account to pay via Paypal if you just want to use a credit card. This can be a good solution for example if your card issuer has problems making transactions in Europe.
Have you activated Verified by Visa?
If you use a Visa card, your card issuer may require Verified by Visa to be activated before you can make purchases.
If you are in the US you can activate it here:
For other countries please contact your card issuer to find out how to activate Verified by Visa.
Have you activated Mastercard Secure Code?
If you use a Mastercard, your card issuer may require Secure Code to be activated in order to make purchases on our store.
You can find out more here: http://www.mastercard.us/securecode.html