我是Angular 2.我正在做YouTube教程，但每个教程都有指令：我被卡住的部分。

app.component.ts

import { Component } from '@angular/core';
import { HeaderComponent } from './components/header/header.component'
@Component({
  selector: 'my-app',template: '<h1>Hello</h1><header></header>',directives: [HeaderComponent]
})
export class AppComponent { }

错误输出为：

Argument of type '{ selector: string; template: string; directives: typeof HeaderComponent[]; }' is not assignable to parameter of type 'ComponentMetadataType'.at line 6 col 3

header.component.ts

import { Component } from '@angular/core';

@Component ({

  selector: 'header',template: '<h2>hit!</h2>'

})
export class HeaderComponent { }

以下是错误的屏幕截图

@NgModule({
  imports:      [ BrowserModule ],declarations: [ AppComponent,HeaderComponent ],<== here
  bootstrap:    [ AppComponent ]
})
export class AppModule { }