iPhone 4s app waiting and dissapearing

I tried to install an app on my iPhone today. After entering the password, the apps' icon appeared and under it the text "Waiting". In under a second, the icon dissapeared. I tried installing the app again - the same thing. I tried to install another app, rebooted the phone - nothing, the app would just dissapear after the Waiting message. Finally, I checked the appstore account - it was a wrong one... When testing in app purchase for iLovePiano I used a test accounb that seems to forbid installing apps. Changed the account back and now it's all fine.