 <p>I think you have to Override this two Methods in <strong>GameFragment</strong> </p> <pre><code> @Override public void onAttach(Activity activity) { super.onAttach(activity); if (activity instanceof Listener ) { mListener = (Listener) activity; } else { throw new ClassCastException(activity.toString() + " must implemenet GameFragment.Listener"); } } @Override public void onDetach() { super.onDetach(); mListener= null; } </code></pre> <p>for more detail Read this <a href="http://www.vogella.com/articles/AndroidFragments/article.html" rel="nofollow">Tutorial</a></p> <p><strong>EDIT</strong></p> <p>And Don't Forget to Initialize Fragment in Activity</p> <blockquote> <pre><code> // Create an instance of GameFragment GameFragment mGameFragment= new GameFragment(); // Add the fragment to the 'fragment_container' Layout getSupportFragmentManager().beginTransaction() .add(R.id.fragment_container, mGameFragment).commit(); </code></pre> </blockquote>