Angularjs with jquery auto complete not working

I am trying for the past 5 hours without success... Here is the code..

In View:

<input type="text" ng-model="foo" auto-complete/>Foo = {{foo}}

In controller:

    myapp.directive('autoComplete', function(autoCompleteDataService) {
    return {
        restrict: 'A',
        link: function(scope, elem, attr, ctrl) {
            elem.autocomplete({
                source: autoCompleteDataService.getSource(), //from your service
                select: function( event, ui ) {
                    scope.foo= ui.item.label;
                    scope.$apply;
                },
                change:function (event, ui) {
                    if (ui.item === null) {
                        scope.foo = null;
                    }
                },
                minLength: 2
            });
        }
    };
});

    myapp.factory('autoCompleteDataService', [function() {
    return {
        getSource: function() {
            return ['apples', 'oranges', 'bananas'];
        }
    }
}]);

Here is the issue...

The selected item is getting into the input box, but foo variable next to input box is not updating.

Where is the mistake.

Please suggest...