Itunes inapp purchases

Okay so yesterday was my birthday and my grandmother purchased a 100$ gift card through paypal, the code was sent to my email where I reedemed it to my Apple ID. So as a young boy I decided to spend my money on a game (in specificaly Clash of Clans) so I was about to buy the 100$ In-app purchase. So I entered my password for my Apple ID but to my surprise it says 'Cannot connect to iTunes store' every time I try. I have tried many resolutions suggested by other users with similar problems such as:

-Restarting my device

-Logging out then back in

-Logging out then logging in when I purchase the in-app purchase.

If anybody has found any solutions to this problem please respond ASAP. Than you very much for all your support, seeing how apple obviously doesn't care as long as they get thier money. 😕