Angular 2：为什么routerLink不将“router-link-active”类添加到我的指令模板中的链接？

Question

这是我的主要组件的精简版本，它被引导，定义了一条路线。

import { Component } from "angular2/core";
import {
    RouteConfig,
    ROUTER_DIRECTIVES,
    ROUTER_PROVIDERS
} from "angular2/router";

import { DashboardComponent } from "./components/dashboard/dashboard.component";

@RouteConfig([
  {
    path: "/dashboard",
    name: "Dashboard",
    component: DashboardComponent,
    useAsDefault: true,
  },
])
@Component({
  selector: "my-app",
  templateUrl: "app/app.component.html",
  directives: [
    ROUTER_DIRECTIVES
  ],
  providers: [
    ROUTER_PROVIDERS
  ]
})
export class AppComponent {}

并且在主要组件的相应HTML中，router-link-active类被添加到活动链接。

<nav class="global-navigation">
    <a [routerLink]="['Dashboard']">View All</a>
    <a [routerLink]="['Tag',{tagName:'CSS'}]">CSS</a>
</nav>
<main class="main-content">
    <router-outlet></router-outlet>
</main>

仪表板组件：

import { Component } from "angular2/core";
import { NotesList } from "../../components/notes-list/notes-list.component";
import { ROUTER_DIRECTIVES } from "angular2/router";

@Component({
  selector: "my-dashboard",
  templateUrl: "app/components/dashboard/dashboard.component.html",
  directives: [NotesList, ROUTER_DIRECTIVES]
})
export class DashboardComponent {}

在仪表板HTML中，路由器链接活动类未添加到活动链接。

<orbital-notes-list></orbital-notes-list>

<a [routerLink]="['Tag', {tagName:'CSS'}]">Testing</a>
<a [routerLink]="['Dashboard']">Back</a>

我找不到解决方案。我肯定错过了一些东西。