Why is "Restricted Card" displayed during checkout/payment?
Government or corporate purchase cards are often restricted from making online purchases that have nothing to do with the agency or company.

We recommend you to call the number on the back of your card and talk to a customer representative of your bank. Please explain to them that you are trying to place an order online and request them to allow the transaction. If they can't help you, you can try to use an alternate method of payment such as PayPal (you can try your card again using PayPal), or simply using a different credit card.
See also:
  1. What is express check out?