I guess you have had this answered, as the post is old. But for others, because this problem is still valid:
This is an old problem. As you posted in English, I suspect you are trying to replay BBC Entertainment. This channel does not have the “Replay” function, so for whatever reason known only to Swisscom, it will not replay on “Air”, only on your TV. You will be able to watch other recordings for channels that have replay.
The error message is erroneous!
Swisscom should sort out this error message as it still comes up today, 3 years after your post and, as you say, you do not register devices.
They should also put replay on BBC Entertainment.