In app purchases

So I finally bought an iPhone and got my favorite game loaded but I am an able to make in app purchases. I made sure to upload my payment information under my Apple ID. It shows in iTunes area and it’s been verified by my bank. But when I try to complete the purchase it says it cannot connect to iTunes and declines the purchase . It sends me to www.apple.com/iTunes/support/WW/. But I can’t find anything to do on there other than what I’ve done. Has anybody else had this problem or know how I can solve it. Thanks for your help!