title: Adding fragments to Back stack
body: <p>I am trying to understand the working of back stack with Fragments
  I am adding multiple fragments within a transaction</p>
  
  <pre><code>FragmentTransaction ft=fm.beginTransaction();
  
      ft.replace(R.id.lay,new fragment2());
      ft.replace(R.id.lay,new fragment3());
  
      ft.addToBackStack("multiple");
  
      ft.commit();
  </code></pre>
  
  <p>However when i popupbackstack with</p>
  
  <pre><code>fm.popBackStack("multiple",0);
  </code></pre>
  
  <p>nothing happens.
  If i use the flag</p>
  
  <pre><code>FragmentManager.POP_BACK_STACK_INCLUSIVE
  </code></pre>
  
  <p>things are working.
  Kindly update why earlier is not working</p>