In-app purchases not working!!! HELP PLEASE(:

So I am totally addicted to the game Crossme Color. My mom said she would let me use some of her iTunes money to get the premium version. So I logged into her account and tried to buy it. At first it was saying a bunch of bs about payment options and security questions. Then once my mom fixed all that it kept asking me if I still wanted to buy it. I kept clicking buy and coming up with other stuff, then the last time it asked me if I still wanted to buy it, it froze and now when I go into the app and try and get the premium version it says it is unable to be purchased. Anyone know how I am able to fix this at all??