The credit card needs to be in your possession and registered under your name. Otherwise, the money won't be credited to your FIAT wallet. Additionally, the credit card has to be either a Mastercard with 3D-secure or a Visa card with Verified-by-Visa activated.
Furthermore, there is a 24h limit of 2,500 EUR for deposits with credit cards. Please check if your deposits are within the boundary.
Please check back with your credit card provider to see what the problem might be. Unfortunately, issuers do not provide us with any data when we ask. Ask them if the security feature is active on your card, and if the funds you need are available.
Also please check carefully if you entered the correct card number, expiration date and CVV.
In case you are only allowed to deposit or trade small amounts, please check if there is a limit in your credit card account. It may occur, that some banks place Bitcoin and other cryptocurrencies in the same category like internet games or gambling, resulting in low limits or sometimes a complete block of related payments.
If none of the problems seen above applies to you, write us and when doing this, please tell us directly the name of the bank issuing your card.