event bind method does not working

I have added below code in controller but it does not works
TypeError: Cannot read property 'on' of undefined

I also tried mediaPlayer insteadof playerName
please suugest playerName comes from, (it seems it's undefined)
$scope.playerName.on( 'load', function( evt ) {
// Tell someone a song is gonna get loaded.
console.log( evt );
} );

No file or test is named; start by reproducing the controller snippet with the AngularJS directive around the audio or video player. Trace how the directive exposes the player reference and compare it with the documented event-binding entry point; done means the undefined-reference error is explained and a verified binding path is identified.

Written by the indexing model from the issue text.