Asking for computer Authorisation.PC already authorised

I am on a sea voyage and therefore have very limited access to the internet.

In my cabin I have my laptop computer, loaded with Movies and TV shows which have been bought and downloaded from iTunes.

The local network within my cabin is from an Apple Airport Express, which in turn streams to the Apple TV which is connected to the cabin TV by HDMI.

The problem that I am experiencing is that when I try to stream a TV Show, or a
Movie, from the computer via the devices mentioned, to the TV set the following
error sign appears on the TV screen.

“! Authorisation is required to play this content on your Apple TV, choose
Authorise This Computer from the Store menu in iTunes on your computer, then
enter the Apple ID and Password used for the purchases.”

I have attempted to carry out these instructions, but told that this computer is already
authorised.

I can stream music, photos and home movies, so the connection is there, but not the purchased movies and TV shows.

Please advise what the problem may be, and the remedy.

Regards

Bruce Floyd

Bruce Floyd