使用ng-click

Question

我在获取文本框的值时获得undefined，这很奇怪，因为我在其他控制器中完美地完成了这一操作。我错过了什么或什么

app.controller('expandCtrl', function($scope, $stateParams) {
  $scope.get_logged_status = sessionStorage.getItem('logged_status');
  console.log('Expand Message Logged Status: ' + $scope.get_logged_status);
  if($scope.get_logged_status == 'false')
  {  window.location ='#/login'; }

  $scope.getPassedId = sessionStorage.getItem('passedId');
  $scope.getPassedFrom = sessionStorage.getItem('passedFrom');
  $scope.getPassedMessage = sessionStorage.getItem('passedMessage');

  $scope.sendReply = function(){
    console.log($scope.txtReply); <----- HERE!
  }

})

我的HTML

<ion-view cache-view="false"  view-title="{{ getPassedFrom }}">
  <ion-pane>
    <br><br><br>
    <div class="padding">
        <p>{{ getPassedMessage }}</p>

        <div class="list list-inset">
            <ion-item>
                <textarea rows="5" style="resize:none" ng-model="txtReply"></textarea>
            </ion-item>
            <button class="button button-block button-energized" ng-click="sendReply()">
              Reply
            </button>
        </div>
    </div>
  </ion-pane>
</ion-view>

编辑：我已经尝试声明$ scope.txtReply ='';并记录为this.txtReply仍然返回null;