Got $10 on my Apple ID buy won't let me purchase any in game stuff

I Used an app called "cash for app" and I succesfully earned a $10 gift card and it was succhess fully added onto my Apple account. But when I go into a game (clash of clans) to buy a $9.99 package of gems it says "not enough money" but when I go into the App Store at the very bottom it says I have $10. So why is it not working??? I just switched phones from droid to an iPhone so my apple account is a gmail. And on my game I have the same gmail on it and my apple account so why is it not working?