title: android.support.v4.app.FragmentTransaction required
body: <p>entering in code like this:</p>
  
  <pre><code>FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
  </code></pre>
  
  <p>comes up with this error "android.support.v4.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();" and has this as a quick fix which does in fact remove the error:</p>
  
  <pre><code>android.support.v4.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
  </code></pre>
  
  <p>and i am typing this in my main activity which extends  FragmentActivity . Does anybody know why? i have included:</p>
  
  <pre><code>import android.support.v4.app.Fragment;
  import android.support.v4.app.FragmentActivity;
  import android.support.v4.app.FragmentManager;
  import android.support.v4.app.FragmentPagerAdapter;
  import android.support.v4.view.ViewPager;
  </code></pre>
  
  <p>EDIT</p>
  
  <pre><code> DescriptionFragment fragment = new DescriptionFragment();
              android.support.v4.app.FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
              ft.replace(R.id.pager, fragment);
              ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
              ft.commit();
  </code></pre>
  
  <p>changing getSupportFragmentManager() to getFragmentManager() requires me to change DescriptionFragment to android.app.Fragment...any ideas?</p>