I recently upgraded my daughters cell phone to my wife's old iphone. I successfully imaged my wifes old phone (4) to her new one (4s). I then restored that phone to factory settings create my daughters. I was adding music from iTunes, which I also sync to my iphone (4). Some of the songs are showing as greyed out on her device. They show up fine, and can be played on mine. It seems to be somewhat random - sometimes, track 01 is there and the others aren't, sometimes the whole album is not there, sometimes a single song that's on a playlist is greyed, sometimes they are there. I did another factory reset and reinstall on her phone with the same results.