Apple Pay trouble

• If you are getting a message to contact the card issuer, call the bank or credit card company who issued you the card to make sure there are no restrictions on the card. 
• If you are getting a message that Apple Pay services are unavailable at this time, sign out of your Apple ID and back in.
• How to use Wallet on your iPhone, iPod touch, and Apple Watch - Apple Support,
• Manage the cards that you use with Apple Pay - Apple Support
• If you have trouble adding a card to wallet;

1. Sometimes if you sign out of your Apple ID and back in it resolves the problem.
2. Check your Apple ID region to make sure it is correct. If it is correct, you may need to select the same region again. (Change your Apple ID country or region - Apple Support)
3. Check the region on your device to ensure it is correct (Settings>general>language & region - set to your region)
4. A passcode is required to use the Wallet app. 
5. You need to be in a region that supports Apple Pay - Countries and regions that support Apple Pay - Apple Support
6. Your bank needs to support Apple Pay - Apple Pay participating banks - Apple Support
7. If none of these suggestions are able to resolve your issue you can go here for further assistance - If you can't add cards to Wallet for Apple Pay - Apple Support

Try removing the card and adding it again. Also make sure cellular data is active. I had this issue the other day when adding my card and I simply just had to remove it and re-add it.

Did you use the links I provided?