Problems adding cards and making payments can happen for different reasons. If your payment information is entered correctly, please call your bank or credit card company to find out if there are any problems. They may need to whitelist the payment, or there may be an issue with your card.
Understanding payment error messages and error codes
If you see an error message when adding a card or making a payment, or if you receive an email that your payment has failed, the details in the message can help you determine the problem. Some error messages and/or payment failure emails contain numeric error codes. This list of credit card error code explanations can provide some insight to what the problem may be.