If you are unable to complete the credit card validation process, please check that the CVC codes match. Please also make sure you are not using a prepaid credit card or gift card. Remember that our credit card processing company (Stripe) only accepts VISA, Mastercard, American Express, JCB, Discover or Diners Club.
If you have checked and your card will still not validate, please send us the exact error message that is displayed and we will forward your ticket to the QA department for testing and debugging.
Have a great day and thanks for using BrickLink!