IPA problem

[abc03zyx]

Dear Skyz,

Long time no see. Recently, I tried to download free apps from apple store. In the process of working through ITunes I was asked to do some registeration for apple account and then ask to authorize the computer to install the ipa. Everything so far so good.

But tonight, I have download ipa from other source, then the as usual I put it to Itunes for download to Ipad. Same as the time I dowload free apps from apple store, Itune as to click for authorization for installation. But this time, the ipa could not be added to the ipad but just repeatly asked for authorization.

So Skyz, what have I done wrong and what should I do. It appears the Itune is able to detect ipa not from apple store and restrict it from adding to ipad.

Thanks.