iTunes won't sync to my iPad
I have a Mac, iPad and iPhone - the newest is a year old.
My iPhone 5S syncs using the USB cable, but the iPad Air generates a message that it won't sync because the Computer is no longer authorised for the items on the iPad.
When authorising it, I get the message it is already authorised.
I have unauthorised and reauthorised the computer. Nothing changes. It used to work and I have changed no settings.
Help!
iPad Air Wi-Fi, iOS 8.1.2