Angular2 mdl-dialog-service-loaded组件不订阅发出的事件

Question

我有一个在应用程序级别注册的中央服务，其任务是保持并发送所有组件的模型的最新状态：

import { Injectable } from '@angular/core';
import { Subject }    from 'rxjs/Subject';

import { Feature } from '../models/Feature.model'


@Injectable()
export class CentralService {

  private feature = new Subject<Feature>();

  feature$= this.feature.asObservable();

  emitToFeature(feature: Feature) {
    this.feature.next(feature);
  }

}

从我的一个组件中我发出一个功能并显示一个mdl对话框（来自angular2-mdl）：

import { Component, OnInit } from '@angular/core';
import { FeatureComponent } from '../feature/feature.component'
import { MdlDialogService } from 'angular2-mdl';
import { CentralService } from '../services/central.service';

@Component({
    ...
    providers:[TaskListService]
})
export class TaskListComponent implements OnInit {

   feature: any=[];
   constructor(
     public dialogService: MdlDialogService,
     private centralService: CentralService){
   }

   addToFeature(value, task){

     if(value==true){
       this.feature.push(task)
       this.centralService.emitToFeature(this.feature)
     }
     else{
       let index: number = this.feature.indexOf(task)
       if (index !== -1) {
         this.feature.splice(index, 1);
         this.centralService.emitToFeature(this.feature)
       } 
     }
   }

   openDialog(){

     this.dialogService.showCustomDialog({
      component: FeatureComponent,
      animate: true,
      isModal: true,
      styles: {'width': '800px', 'max-height':'500px' ,'overflow-y':'scroll'},
      clickOutsideToClose: true

    })

   }
}

该对话框基本上显示了FeatureComponent：

import { Component, OnInit, AfterContentInit } from '@angular/core';
import { CentralService } from '../services/central.service';

@Component({
    ...
})
export class FeatureComponent implements OnInit, AfterContentInit {

    constructor(
        private centralService: CentralService
        ) { 
    }

    ngOnInit() {
    }

    ngAfterContentInit(){

        this.centralService.feature$.subscribe(

            feature => {
                console.log('In Feature component ', feature)
            }
            )

    }

}

对话框正确加载并显示FeatureComponent的模板，但不知何故它不从中央服务获取功能。我尝试在ngOnInit（）和构造函数中编写它，但没有帮助。

对话框插座位于app.html：

<app-header></app-header>
<dialog-outlet></dialog-outlet>
<router-outlet></router-outlet>

注意：没有在ngAfterContentInit（）中编写的控制台语句。我做错了什么？