They're different reasons to why your card may have been rejected while trying to use it to fund your wallet, first check their banking page to see the types of card they accept for payments, this is the first step to identifying the issue most casino websites doesn't accept verve card.
Secondly check your account balance, it may be that the amount in your bank account is less than the amount you wish to fund into your casino wallet and that's why the transaction is failing, if you didn't find any issues with any of the reasons I listed, contact the casino website team.
Secondly check your account balance, it may be that the amount in your bank account is less than the amount you wish to fund into your casino wallet and that's why the transaction is failing, if you didn't find any issues with any of the reasons I listed, contact the casino website team.