ng-click not firing first time works second time works

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AngularJs

I have data service hold booking from questions and

app.factory('QuestionService',function(){
 ..........
  vm.goNext = function () {
                 var clearAnswersPromise = vm.clearInvalidAnswers();

                $q.all([clearAnswersPromise]).then(function (data) {
                    vm.checkForInvalidAnswers();
                }).then(function () {
                    vm.processNextFinal();//this will make $http call
                });
..........

});

 app.controller('formCtrl',function(QuestionService){
       var vm = this;
        vm.QuestionService = QuestionService;
 

});

............
 <button class="button--primary button pull-right bc-questions"  type="button" ng-click="vm.QuestionService.goNext ()">
                        Next
                    </button>
..............

For first time it works, but after i go to the next page, then i come back to this form modify some information, this time when I click, the button won't do anything, must click the second time then works.

It seems very strange, has anyone know how to solve this issue? Since this just don't fire event, and don't seems that have any logic issue. I am totally lost :(