The code within Player Disconnected will run when the player has disconnected although the debugger won't be called. It should run if you click the disconnect button in the Test Harness, what are you trying to do with your code in this script ? You can debug it in a test script and then place it in Player Disconnected when you know it fully works.
I think i found the problem. i connect with unity. then i connect with test harness. i disconnect unity. it will not call PlayerDisconnected Event. i disconnect test harness.it will not call PlayerDisconnected Event. i reconnect unity. i disconnect unity. it will call PlayerDisconnected Event.
i guess; you have a connection counter. you do not decrease connection count if there is another connection.