Angular 2 Nested ng For Not Woring

Question

上面提到的代码无法正常显示我的控制台中的错误

<ul *ngFor="let value of Course.module" class="list-unstyled lesson-order-wrapper" ><!--[dragula]="zero-bag" -->
    <li class="lesson-container closed" id='less{{value.id}}'> 
        <div class="lesson-headding " (click)="slideUpnDown(value.id)">{{value.module_name}} <span class="icon-down-arrow pull-right panel-icon"></span></div>
        <div class="sub-lessons"  >
            <ul class="list-unstyled" *ngFor="let val of Course.OrderView[value.id]" [dragula]="value.module_name" id="1">
                <li class="lesson-titles">{{val.quiz_title}}</li>
            </ul>
        </div>
    </li>
</ul>

错误：

  

AdminCourseOrderComponent.html：24错误错误：找不到差异   支持对象＆＃39; [对象]＆＃39;类型＆＃39;对象＆＃39;。仅限Ng   支持绑定到诸如Arrays之类的Iterables。