title: java.lang.IllegalStateException: Action Bar Tab must have a Callback
body: <p>I am trying to add an <code>ActionBarSherlock</code> with 4 tabs to my application.
  I tried to extend from SherlockActivity<code>then</code>SherlockFragmentActivity`, but I still get this Exception:</p>
  
  <blockquote>
    <p>java.lang.IllegalStateException: Action Bar Tab must have a Callback.</p>
  </blockquote>
  
  <pre><code>    import java.io.IOException;
      import java.net.URL;
  import java.util.ArrayList;
  import java.util.List;
  
  import org.apache.http.NameValuePair;
  import org.apache.http.client.ClientProtocolException;
  import org.apache.http.client.HttpClient;
  import org.apache.http.client.ResponseHandler;
  import org.apache.http.client.entity.UrlEncodedFormEntity;
  import org.apache.http.client.methods.HttpPost;
  import org.apache.http.impl.client.BasicResponseHandler;
  import org.apache.http.impl.client.DefaultHttpClient;
  import org.apache.http.message.BasicNameValuePair;
  import org.apache.http.params.BasicHttpParams;
  import org.apache.http.params.HttpParams;
  import org.apache.http.params.HttpProtocolParams;
  import org.json.JSONArray;
  import org.json.JSONObject;
  
  import com.actionbarsherlock.app.ActionBar;
  import com.actionbarsherlock.app.ActionBar.Tab;
  import com.actionbarsherlock.app.ActionBar.TabListener;
  import com.actionbarsherlock.app.SherlockActivity;
  import com.actionbarsherlock.app.SherlockFragmentActivity;
  import com.actionbarsherlock.view.Menu;
  import com.actionbarsherlock.view.MenuInflater;
  import com.actionbarsherlock.view.MenuItem;
  
  import twitter4j.Status;
  import twitter4j.Twitter;
  import twitter4j.TwitterException;
  import twitter4j.TwitterFactory;
  import twitter4j.auth.AccessToken;
  import twitter4j.auth.RequestToken;
  import android.app.Activity;
  import android.app.AlertDialog;
  import android.app.ProgressDialog;
  import android.content.Context;
  import android.content.Intent;
  import android.content.SharedPreferences;
  import android.os.AsyncTask;
  import android.os.Bundle;
  import android.os.StrictMode;
  import android.preference.PreferenceManager;
  import android.support.v4.app.FragmentTransaction;
  import android.util.Log;
  import android.view.LayoutInflater;
  import android.view.View;
  import android.view.ViewGroup;
  import android.view.View.OnClickListener;
  import android.widget.AdapterView;
  import android.widget.AdapterView.OnItemClickListener;
  import android.widget.ArrayAdapter;
  import android.widget.Button;
  import android.widget.EditText;
  import android.widget.ListView;
  import android.widget.TextView;
  import android.widget.Toast;
  
  public class HomeActivity extends SherlockFragmentActivity implements OnClickListener, OnItemClickListener, TabListener {
  
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          // TODO Auto-generated method stub
          super.onCreate(savedInstanceState);
          setContentView(R.layout.homelayout);
          try{
  
              ActionBar actionBar = getSupportActionBar();
              actionBar.setDisplayHomeAsUpEnabled(true);
              actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
  
              Tab homeTab = actionBar.newTab();
              homeTab.setIcon(R.drawable.tab_home);
              Tab exploreTab = actionBar.newTab();
              exploreTab.setIcon(R.drawable.tab_explore);
              Tab leaderBoardTab = actionBar.newTab();
              leaderBoardTab.setIcon(R.drawable.tab_leaderboard);
              Tab profileTab = actionBar.newTab();
              profileTab.setIcon(R.drawable.tab_profile);
  
              actionBar.addTab(homeTab);
              actionBar.addTab(exploreTab);
              actionBar.addTab(leaderBoardTab);
              actionBar.addTab(profileTab);
                       }catch(Exception ex){
  
              Log.e("error from onCreate" , ex.toString());
              Log.e("error from onCreate" , ex.getStackTrace().toString());
              }
  
                 }
  
      @Override
      public void onTabSelected(Tab tab, FragmentTransaction ft) {
          // TODO Auto-generated method stub
  
      }
  
  
  
      @Override
      public void onTabUnselected(Tab tab, FragmentTransaction ft) {
          // TODO Auto-generated method stub
  
      }
  
  
  
      @Override
      public void onTabReselected(Tab tab, FragmentTransaction ft) {
          // TODO Auto-generated method stub
  
      }
  }
  </code></pre>