Angular ngSrc image not found directive

gistfile1.js

app.directive('errSrc', function() {
  return {
    link: function(scope, element, attrs) {

      scope.$watch(function() {
          return attrs['ngSrc'];
        }, function (value) {
          if (!value) {
            element.attr('src', attrs.errSrc);
          }
      });

      element.bind('error', function() {
        element.attr('src', attrs.errSrc);
      });
    }
  }
})

gistfile2.html

 <img ng-src="{{getADImageURL(ad)}}" err-src="{{notfound}}" />

gistfile3.js

angular.module('myApp.controllers').controller('ADCtrl', ['$rootScope', '$scope', '$log', 'API_EVENTS', 'ServerConfig', 'AlertService', '$location', 'blockUI', 'ADService', '$sce', 'dialogs', '$filter',
	function($rootScope, $scope, $log, API_EVENTS, ServerConfig, AlertService, $location, blockUI, ADService, $sce, dialogs, $filter) {
		$log.log('load ad page');

		var notfoundImg = ServerConfig.endpoint + 'app/assets/images/404_img.png';
		// alert(notfoundImg);
		$scope.notfound = notfoundImg;
		
	}
	]);