I have an iPhone 5s and so does my mother. I recently updated both to 9.1. My MBP is snow leopard and itunes is 11.4. I updated my mother's phone first. Then I updated mine. I went to back up mine and it said this message with itunes: The iPhone cannot be used because it requires a newer version of iTunes. Go to www.itunes.com to download the latest version of iTunes. So I tried to back up my mother's and it works FINE with itunes! Why would that be?! It is the 5s, same ios, same computer. Any body know why?