title: Angularjs ng-disabled button for several checkbox input
body: <p>I have the following plunler : </p>
  
  <p><a href="http://plnkr.co/edit/ZJq0Qy3j5nGr1eJ9f9QA?p=preview" rel="nofollow">http://plnkr.co/edit/ZJq0Qy3j5nGr1eJ9f9QA?p=preview</a></p>
  
  <p>What I'd like to do is to enable the button if at least one checkbox is checked.</p>
  
  <pre><code>&lt;button class="btn btn-danger" ng-click="removeSelectedRows()"&gt;Remove Selected Rows&lt;/button&gt;
  </code></pre>
  
  <p>This works great :</p>
  
  <pre><code>&lt;button ng-disabled="mySwitch"&gt;Click&lt;/button&gt;
  &lt;input type="checkbox" ng-model="mySwitch"&gt;
  </code></pre>
  
  <p>but when I apply it to my example, it does nothing.</p>
  
  <p>Any advice ?</p>