Cannot choose AirPort Express for Mac system audio output
Music playback from iTunes to my Airport Express works fine.
On the same Mac, Airport Express is listed as an AirPlay device in System Preferences > Sound. When I choose it, I get a message saying "Could not connect to ...'s Airport Express".
What could be the problem?
MacBook Pro Mid 2010, Mac OS X El Capitan 10.11.6, iTunes 12.6.3.6
Airport Express MC414Z/A with firmware 7.8 as wireless access point
MacBook (Starting Late 2009)