Infinity blade invalid ipa?

hello there i have a problem with Infinity blade, every time i try to install it a window opens up and says invalid ipa i have tried every version and it doesn't work. I have an ipod touch 3 generation and i install it from installous 4 and i have the newest version of appsync my ipod is currently on 4.2.1 i have tried every thing but doesn't?????? please help!!!!