Madden mobile not letting me purchase in app

[deadbabysolider]

whenever i open the madden mobile app a message pops up saying "Sign into Itunes Store. if you have an Apple ID, Sign in with it here. [Environment: Sandbox] " then it says cancel or buy, i click buy try typing in my password and it says my password is incorrect, this is the only app it doesn't recognize my password, I try making purchases on the app and it wont recognize my password.

[EA_Barry]

Try signing in first, before you open the App. so that when you go to make the purchase you are already signed in.