Problems with payment for a realm

Hello

I'm from Belgium and I'm trying to buy a realms for me and my friends but when I try this, I always have problems with my creditcard. It's a prepaid card from KBC and I always get an error that says my data is incorrect. I have tried at least ten times now.
The error I always receive is: An error occurred while placing order, please verify credit card info and try again.
Can you please help me.

Thank you in advance.

Nicolas