When trying to apply a coupon code, you will need to make your ticket selection(s) first. After you clock checkout, but before you start to enter information into the details form, there is a box on the right, highlighted by the picture below.
The coupon code box will disappear after you click continue, and does not come back unless you navigate back to the Buyers Details section of checkout.
After entering the coupon code in the box, remember to hit the enter key. The coupon code should turn green, and should appear in the list of items in your cart.
Multiple Coupon Codes
At the moment, there is no way to use multiple coupon codes with Wix. It is a feature that has been requested, but has not yet been acted upon.
We are working on a solution that will let you combine coupon codes, but at the moment, please contact email@example.com with the coupons that you need combined.