title: ExpandableListView does not append the childs
body: <p>I have an ExpandableListView containing movie information. The groups are the movie titles, the childs are the media related to this movie (all included in the Movie object).
  The ExpandableListView is showed but only with the groups, and when I click on them, the list does not expand. I debugged it and i figure out the getChildView is never executed.
  I was searching but i cant realize why this method is not being executed. </p>
  
  <pre><code>ArrayList&lt;MovieMock&gt; movies;
  @Override
  public void onCreate(Bundle savedInstanceState){    
      super.onCreate(savedInstanceState);
  
      setContentView(R.layout.savedsyncs_content);
  
      ExpandableListView l = (ExpandableListView) findViewById(R.id.ExpandableList_Content);
  
      laodMockedList();
  
      ContentExpandableListAdapter adapter = new ContentExpandableListAdapter(this, movies);
      l.setAdapter(adapter);
  }
  
  public class ContentExpandableListAdapter extends BaseExpandableListAdapter {
  private ArrayList&lt;MovieMock&gt; movies;    
  private Context context;
  
  /*ExpandableList containing the movies from SavedSyncs. The groups are the movie's titles, the childs are 
   * the movie media and information.
   * */
  public ContentExpandableListAdapter(Context context, ArrayList&lt;MovieMock&gt; movies){
      this.context = context;
      this.movies = movies;
  }
  
  @Override
  public boolean areAllItemsEnabled()
  {
      return true;
  }
  
  @Override
  public MovieMock getChild(int groupPosition, int childPosition) {
      // TODO Auto-generated method stub
      Log.d("CHILD", "getChild : " + groupPosition);
      return movies.get(groupPosition);
  }
  
  @Override
  public long getChildId(int arg0, int arg1) {
      // TODO Auto-generated method stub
      //return Long.parseLong(movies.get(arg0).getId());
      return arg1;
  }
  
  @Override
  public View getChildView(int groupPosition, int childPosition, boolean isLastChild,View convertView, ViewGroup parent) {
      MovieMock child = (MovieMock)getChild(groupPosition, childPosition);
      Log.d("DEBUG", "Entro al hijo") ;
      if (convertView == null) {
          LayoutInflater infalInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          convertView = infalInflater.inflate(R.layout.expandablelistcontent_child, null);
      }
  
      TextView audiotxt = (TextView) convertView.findViewById(R.id.audio_text);
      audiotxt.setText(child.getAudio());
  
      /*TextView videotxt = (TextView) convertView.findViewById(R.id.video_text);
      videotxt.setText(child.getAudio());*/
  
      return convertView;
  }
  
  @Override
  public int getChildrenCount(int groupPosition) {
      // TODO Auto-generated method stub
      return 3;
  }
  
  @Override
  public String getGroup(int groupPosition) {
      // TODO Auto-generated method stub
      return movies.get(groupPosition).getTitle();
  }
  
  @Override
  public int getGroupCount() {
      // TODO Auto-generated method stub
      return movies.size();
  }
  
  @Override
  public long getGroupId(int groupPosition) {
      // TODO Auto-generated method stub
      //return Long.parseLong(movies.get(groupPosition).getId());
      return groupPosition;
  }
  
  @Override
  public View getGroupView(int groupPosition, boolean isExpanded,
          View convertView, ViewGroup parent) {
      String movieTitle = (String) getGroup(groupPosition);
  
      if (convertView == null) {
          LayoutInflater infalInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
          convertView = infalInflater.inflate(R.layout.expandablelistcontent_group, null);
      }
  
      TextView grouptxt = (TextView) convertView.findViewById(R.id.ContentText);
  
      grouptxt.setText(movieTitle);
  
      return convertView;
  }
  
  @Override
  public boolean hasStableIds() {
      // TODO Auto-generated method stub
      return false;
  }
  
  @Override
  public boolean isChildSelectable(int groupPosition, int childPosition) {
      // TODO Auto-generated method stub
      return true;
  }
  
  }
  </code></pre>
  
  <p>And here is the XML code:</p>
  
  <p>The Group:</p>
  
  <pre><code>&lt;RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"&gt;
  &lt;TextView
      android:id="@+id/ContentText" 
      android:text="Content"
      android:layout_width="wrap_content"
      android:layout_height="40dip"
      android:layout_alignParentLeft="true"
      android:layout_centerVertical="true"/&gt;
  &lt;ImageButton 
      android:id="@+id/delete_button" 
      android:layout_width="20dip" 
      android:layout_height="20dip" 
      android:background="@drawable/delete_button"
      android:layout_alignParentRight="true"
      android:layout_centerVertical="true"
      &gt;
  &lt;/ImageButton&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>
  
  <p>The child:</p>
  
  <pre><code>&lt;RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"&gt;
  &lt;LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:id="@+id/layout_audio"&gt;
      &lt;ImageView 
          android:background="@drawable/audio_icon" 
          android:layout_height="20dip" 
          android:layout_width="20dip" 
          android:id="@+id/audio_icon"
          &gt;
      &lt;/ImageView&gt;
      &lt;TextView
          android:id="@+id/audio_text" 
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="Audio"
          android:layout_toRightOf="@id/audio_icon"
      &gt;
      &lt;/TextView&gt;
  &lt;/LinearLayout&gt;
  
  &lt;LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:id="@+id/layout_video"
  android:layout_below="@id/layout_audio"&gt;    
  &lt;ImageView 
      android:background="@drawable/video_icon" 
      android:layout_height="20dip" 
      android:layout_width="20dip" 
      android:id="@+id/video_icon"&gt;
  &lt;/ImageView&gt;
  &lt;TextView
      android:id="@+id/video_text" 
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Trailer"
      android:layout_toRightOf="@id/video_icon"
  &gt;
  &lt;/TextView&gt;
  &lt;/LinearLayout&gt;
  &lt;LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:id="@+id/layout_image"
  android:layout_below="@id/layout_video"&gt;
  &lt;ImageView 
      android:background="@drawable/image_icon" 
      android:layout_height="20dip" 
      android:layout_width="20dip" 
      android:id="@+id/image_icon"&gt;
  &lt;/ImageView&gt;
  &lt;TextView
      android:id="@+id/image_text" 
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:gravity="center_vertical"
      android:text="Poster"
      android:layout_toRightOf="@id/image_icon"
  &gt;
  &lt;/TextView&gt;
  &lt;/LinearLayout&gt;
  &lt;LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/layout_info"
  android:layout_below="@id/layout_image"&gt;  
  &lt;ImageView 
      android:background="@drawable/info_icon" 
      android:layout_height="20dip" 
      android:layout_width="20dip" 
      android:id="@+id/info_icon"&gt;
  &lt;/ImageView&gt;
  &lt;TextView
      android:id="@+id/info_text" 
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Movie Information"
      android:layout_toRightOf="@id/info_icon"
  &gt;
  &lt;/TextView&gt;
  &lt;/LinearLayout&gt;
  &lt;/RelativeLayout&gt;
  </code></pre>