Ionic Framework: $scope is undefined in simple alert

.controller('newGoalCtrl', function($scope, $ionicPopup) {
    $scope.addNewGoal = function() {
        alert($scope.goaltitle);
    };
});

<ion-pane view-title="goal">
   <ion-header-bar class="bar-positive">
      <div class="buttons">
          <a nav-transition="android" class="button button-icon icon ion-arrow-left-b" ng-click="" href="#/index"></a>
      </div>
      <h1 class="title">Add New Goal</h1>
    </ion-header-bar>


    <ion-content class="padding" scroll="false" >
        <div class="list">
            <label class="item item-input">
                <input type="text" placeholder="#Title" ng-model="goaltitle">
            </label>
            <label class="item item-input">
                <span class="hashtag-title">#{{hashtagname}}</span>
            </label>
            <label class="item item-input">
              <textarea placeholder="Goal"></textarea>
            </label>
        </div>
    </ion-content>


    <ion-tabs class="tabs-icon-top tabs-color-active-positive">
        <button class="button button-positive button-bar no-round-corner" ng-click="addNewGoal()">Add Goal</button>
    </ion-tabs>
</ion-pane>

This is my code... I don't know how to explain but it always say undefined when I enter something on the text box...

but $scope.goaltitle = "something" is working on the .controller(); ...