Q: I downloaded an app on my iPad 2. Then got an iPad 3 and it won't let me download in app purchases in that app now

I downloaded the simpsons tapped out for iPad, on my iPad 2. Everything worked fine. During the summer I was given an ipad3 and I moved all my apps and stuff to my new iPad, now in the same app it won't let me make in app purchases.... Any help out there