title: ActionBar doesn't show in Android KitKat 4.4.4
body: <p>I'm developing an app in Android and I'm having problem with implementing the ActionBar in a Fragment. </p>
  
  <p>Here's the code of my Fragment:</p>
  
  <pre><code>public class TopicListFragment extends ListFragment {
  
  private LinkedList&lt;Topic&gt; mTopics;
  private static final String TAG = "TopicListFragment";
  
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState); 
      setHasOptionsMenu(true); 
  
      mTopics = TopicLab.get(getActivity()).getTopics();
  
      ArrayAdapter&lt;Topic&gt; adapter =  new TopicAdapter(mTopics);
  
      setListAdapter(adapter);
  }
  
  @Override
      public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
          Log.d(TAG, "Menu created");
          super.onCreateOptionsMenu(menu, inflater);
          inflater.inflate(R.menu.fragment_topic_list, menu);
      }
  </code></pre>
  
  <p>And here's the XML file for the meny layout: </p>
  
  <pre><code> &lt;?xml version="1.0" encoding="utf-8"?&gt;
      &lt;menu xmlns:android="http://schemas.android.com/apk/res/android"
            xmlns:app="http://schemas.android.com/apk/res-auto"
            xmlns:tools="http://schemas.android.com/tools" &gt;
  
          &lt;item android:id="@+id/menu_item_new_topic"
                android:icon="@android:drawable/ic_menu_add"
                android:title="@string/new_topic"
                app:showAsAction="ifRoom"&gt;&lt;/item&gt;
  
      &lt;/menu&gt;
  </code></pre>
  
  <p>When I run the app the ActionBar doesn't show and if I press the menù button from my smartphone, it appears in an ugly botton line with only the title.</p>
  
  <p>As you can see in the Fragment class, I have inserted a line of debug, but it print the message only when I press the menù button but not when the Activity is created. </p>
  
  <p>What can I do to fix it? Every answer will be really appreciated! Thank you!</p>
  
  <p>EDIT----</p>
  
  <p>As asked this is the styles.xml file</p>
  
  <pre><code>&lt;resources&gt;
  
      &lt;!-- Base application theme. --&gt;
      &lt;style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar"&gt;
          &lt;!-- Customize your theme here. --&gt;
          &lt;item name="colorPrimary"&gt;@color/colorPrimary&lt;/item&gt;
          &lt;item name="colorPrimaryDark"&gt;@color/colorPrimaryDark&lt;/item&gt;
          &lt;item name="colorAccent"&gt;@color/colorAccent&lt;/item&gt;
      &lt;/style&gt;
  
  &lt;/resources&gt;
  </code></pre>