Angular2(最终版本)* ngFor in component：无法绑定到’ngForOf

我已经构建了以下组件树：
主要 – >仪表板 – >警报

Unhandled Promise rejection: Template parse errors: Can’t bind to
‘ngForOf’ since it isn’t a known property of ‘div’.

(“<div class=”item” [ERROR ->] *ngFor=”let alert of alerts”>

“): DashboardAlertsComponent@5:20 Property binding ngForOf not used by any directive on an embedded template.

Make sure that the property name is spelled correctly and all
directives are listed in the “directives” section.

它工作正常,但当我尝试在警报组件中添加* ngFor循环时,我收到以下错误：

DashboardAlertsComponent：

import {Component,OnInit} from "@angular/core";
import {Alert} from "../../shared/models/alert.model";

@Component({
  selector: 'dashboard-alerts',templateUrl: './alerts.component.html'
})
export class DashboardAlertsComponent implements OnInit {

  alerts:Alert[] = new Array<Alert>();
  constructor() {
    this.alerts.push(new Alert('1','high','My alert1','12/11/2016 4:50 PM'));
    this.alerts.push(new Alert('2','low','My alert2','11/11/2016 9:50 PM'));
    this.alerts.push(new Alert('3','medium','My alert3','10/11/2016 2:50 PM'));
  }

  ngOnInit() {
  }
}

alerts.component.html

<div class="item" *ngFor="let alert of alerts">
    <span class="priority {{ alert }}"></span>
    <span class="title">{{ alert }}</span>
    <span class="time">3:40 PM</span>
    <a href="#" class="more-actions"><span>Actions</span></a>
</div>

DashboardModule

@NgModule({
  declarations: [
    DashboardAlertsComponent
  ],providers: [],directives: [],})
export class DashboardModule {
}

的AppModule

@NgModule({
  imports: [
    BrowserModule,DashboardModule
  ],declarations: [
    AppComponent
  ],bootstrap: [AppComponent]
})
export class AppModule {
}

P.S我为这个问题阅读了许多建议的解决方案,但没有一个解决了这个问题