I can add my credit card to my wallet on my iMac but NOT on my phone…

Hi! I have an issue with my wallet. I was able to add my credit card to my wallet on my iMac. But when I want to add it to my phone, it keeps jumping back to the screen “add card” every time I click “next”. All the information added, including the security code, has been entered correctly. What could be the problem? Thx!