Airplay keeps asking for onscreen passcode.

Hi. I just bought a Sony Bravia X90H which supports airplay. I am trying to stream from the appleTv app on my iPad to the Sony tv. Both are on the same network. It shows my tv but then asks for a 4 digit passcode which I enter. But it keeps asking for it and won’t accept the code. What am I doing wrong? I also tried streaming from my iPhone but it does the same thing.