Airplay icon in i-Tunes!

The airplay icon in i-Tunes has disappeared! It's been there and worked fine for the last two years! Tried lotsa recommendations including updating i-Tunes, uninstalling/reinstalling, checking to see if i-Tunes and receiver (Yamaha RX-V673) are connected to the same router, etc., etc. Anyone have any idea what may have happened?!!! THANKS!!!