title: angular2 subject not subscribing the change
body: <p>I've two components and a shared service which is shared by the two components.</p>
  
  <p><strong>shared.service.ts</strong></p>
  
  <pre><code>// ..... top level codes are skipped
  
  private pickAnalysisForBubble = new Subject&lt;any&gt;();
  
    analysisForBubble$ = this.pickAnalysisForBubble.asObservable();
  
    mapToggleToPointOrBubble(value) {
      this.pickAnalysisForBubble.next(value);
    }
  </code></pre>
  
  <p><strong>utility.component.ts</strong></p>
  
  <p>in view (utility.component.html), there are two radio button and one is pre-selected:</p>
  
  <pre><code>&lt;input type="radio" name="rdbBubblePoint" class="rdbBubblePoint" value="Point" (change)="changeToPoint($event)"&gt; Point&lt;br&gt;
  &lt;input type="radio" name="rdbBubblePoint" class="rdbBubblePoint" value="Bubble" (change)="changeToPoint($event)" checked="checked"&gt; Bubble&lt;br&gt;
  </code></pre>
  
  <p>in component (utility.component.ts), there is a method to grab the click event: (I've imported the <code>shared.service</code> and added this as a provider.)</p>
  
  <pre><code>changeToPoint(event){
      # analysisInteraction is the shared service constructor
      this.analysisInteraction.mapToggleToPointOrBubble(event.target.value);
  }
  </code></pre>
  
  <p><strong>map.component.ts</strong></p>
  
  <p>I've imported the <code>shared.service</code> and added a constructor. Then in <code>ngOnInit</code> tried to <code>subscribe</code> the change, <em>but this is not working.</em></p>
  
  <pre><code># analysisInteraction is the shared service constructor
  this.analysisInteraction.analysisForBubble$.subscribe(
          data =&gt; {
            this.DrawType = data;
            console.log("Drawtype fixed");
        });
  </code></pre>
  
  <p>I'm using <code>subject</code> to detect the change based on this <a href="https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#bidirectional-service" rel="nofollow">tutorial</a>. What I'm doing wrong?</p>