Problems with the PSN Store and Pre-Paid Credit Cards

[Kickbuttmario]

So yesterday last night I got a pre-paid credit card (mastercard) and tried to use it on the Playstation store to buy FF 9, hence why I made that thread about which FF game to buy. However though I am unable to buy the game because my mastercard information whenever I try to enter it on the billing information on my account is invalid. I went on to the card website and made sure to double check if I registered, and I did. Not to mention Sony charged me $7 for doing the transaction 7 times. I know they said it could be removed in 7 - 10 days but I am confused if anyone knows why or if pre-paid credit cards are even usable on the store. If not, I might as well just spend the money on steam since its useless to use it on the Playstation Store.

And yes, I did enter the billing information correctly, how else did $7 be taken out of the account?

EDIT: Able to add money onto my steam account with this card.