Q: I click "redeem" button on my gift, but it just brings me to the "new" page on iTunes, what is the problem?

Hello jojeka, 

Thank you for using Apple Support Communities. 

I see you are having difficulties in redeeming a gift card for iTunes. I have a couple of articles here for you to take a look at. The first give the basic steps to redeem gift cards on various devices. I would suggest checking that one first to make sure you are not missing any steps. The second is to use if you continue to have issues redeeming them. 

Redeem iTunes Gift Cards with the camera on your iPhone, iPad, iPod touch, or Mac - Apple Support

If you can't redeem your iTunes Gift Card or code - Apple Support

Regards