$state Nagivation doesn't work in my angularjs

The Go button work but it couldn't navigate from page 2 to home. I wonder why? The code look flawless.

<ion-nav-view name="home"></ion-nav-view>
<ion-nav-view name="threadContent"></ion-nav-view>

<script type="text/ng-template" id="home.html">
  <ion-view name="home">
    <ion-content>
      <h2>Home Page</h2>
      <p>Here is the main route for the app.</p>
      <a href="#/threadContent">GO</a>
    </ion-content>
  </ion-view>
</script>

<script type="text/ng-template" id="threadContent.html">
  <ion-view  name="threadContent" title="Thread Content">
    <ion-content>
    <a href="#/home">Back</a>
       <h2>Using the app</h2>
       <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Facilis architecto hic officia quasi excepturi sequi deleniti maiores consectetur veritatis sint?</p>
    </ion-content>
  </ion-view>
</script>

demo http://codepen.io/anon/pen/qEOJBp