. When I enter a valid coupon code, and click "submit", the icon turns into a spinning circle, and does not validate the code. This guide will show you how to add the Coupon Code in addition to the other options that are already available in the Payment Form described on this guide on How to Add Options to Payment Forms. . When I enter a valid coupon code, and click "submit", the icon turns into a spinning circle, and does not validate the code. This guide will show you how to add the Coupon Code in addition to the other options that are already available in the Payment Form described on this guide on How to Add Options to Payment Forms.