Ionic refresher working not properly

I am developing android app using ionicframework.It use a <ion-refresher> to load the contents dynamically when pull down the page,but it didnt work.

           <ion-refresher
                          pulling-text="Pull to refresh..."
                          on-refresh="doRefresh">
            </ion-refresher>

controller

$scope.doRefresh = function() {
              $http.get('http://localhost/test/gksfapp_backend.php?action=an').then(function(msg){
                     //never executed.
                     $scope.items=msg.data;
                     })
                     .finally(function() {
                     // Stop the ion-refresher from spinning
                         $scope.$broadcast('scroll.refreshComplete');
               });