Android - ActionBarSherlock Навигационен панел и фрагменти с дейности

Опитвам се да разбера как да внедря чекмеджето за навигация ActionBarSherlock в проект. Имам един, който работи с официалната реализация на Android, но бих искал да работи на 2.2+, така че търся ActionBarSherlock. Имам грешка в секцията selectItem(int position) на кода. Ще го поставя тук:

package com.rufflez.absnavdrawer;

import com.actionbarsherlock.app.SherlockFragmentActivity;
import com.actionbarsherlock.view.Menu;
import com.actionbarsherlock.view.MenuItem;

import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MainActivity extends SherlockFragmentActivity {
private DrawerLayout mDrawerLayout;
private ListView mDrawerList;
private ActionBarDrawerToggle mDrawerToggle;

private CharSequence mDrawerTitle;
private CharSequence mTitle;
private String[] mFragmentTitles;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mTitle = mDrawerTitle = getTitle();
    mFragmentTitles = getResources().getStringArray(R.array.fragments);
    mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer);
    mDrawerList = (ListView)findViewById(R.id.drawer_list);

    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
    mDrawerList.setAdapter(new ArrayAdapter<String>(this, R.layout.drawer_list_item, mFragmentTitles));
    mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    getSupportActionBar().setHomeButtonEnabled(true);

    mDrawerToggle = new ActionBarDrawerToggle(this, 
            mDrawerLayout, 
            R.drawable.ic_drawer, 
            R.string.drawer_open, 
            R.string.drawer_close){
        public void onDrawerClosed(View v){
            getSupportActionBar().setTitle(mTitle);
            supportInvalidateOptionsMenu();
        }
        public void onDrawerOpened(View v){
            getSupportActionBar().setTitle(mDrawerTitle);
            supportInvalidateOptionsMenu();
        }
    };
    mDrawerLayout.setDrawerListener(mDrawerToggle);
    if (savedInstanceState == null){
        selectItem(0);
    }

}

@Override
public boolean onPrepareOptionsMenu(Menu menu){
    boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
    menu.findItem(R.id.action_settings).setVisible(!drawerOpen);
    return super.onPrepareOptionsMenu(menu);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getSupportMenuInflater().inflate(R.menu.main, menu);
    return true;
}

public boolean onOptionsItemSelected(MenuItem item){
    switch(item.getItemId()){
    case android.R.id.home:
        if (mDrawerLayout.isDrawerOpen(mDrawerList)){
            mDrawerLayout.closeDrawer(mDrawerList);
        } else {
            mDrawerLayout.openDrawer(mDrawerList);
        }
        return true;
    case R.id.action_settings:
        Intent i = new Intent(MainActivity.this, Sources.class);
        startActivity(i);
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

private class DrawerItemClickListener implements ListView.OnItemClickListener{
    @Override
    public void onItemClick(AdapterView<?> parent, View v, int position, long id){
        selectItem(position);
    }
}

private void selectItem(int position){
    Fragment newFragment = new Fragment_1();
    FragmentManager fm = getSupportFragmentManager();
    switch(position){
    case 0:
        newFragment = new Fragment_1();
        break;
    case 1:
        newFragment = new Fragment_2();
        break;
    case 2:
        newFragment = new Fragment_3();
        break;
    case 3:
        newFragment = new Fragment_4();
        break;
    case 4:
        newFragment = new Fragment_5();
        break;
    }
    fm.beginTransaction()
    .replace(R.id.content_frame, newFragment)
    .commit();

    mDrawerList.setItemChecked(position, true);
    setTitle(mFragmentTitles[position]);
    mDrawerLayout.closeDrawer(mDrawerList);
}

@Override
public void setTitle(CharSequence title){
    mTitle = title;
    getSupportActionBar().setTitle(title);
}

@Override
protected void onPostCreate(Bundle savedInstanceState){
    super.onPostCreate(savedInstanceState);
    mDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig){
    super.onConfigurationChanged(newConfig);
    mDrawerToggle.onConfigurationChanged(newConfig);
}

}

Както казах по-горе, грешката е под selectItem и по-специално грешка под new Fragment_1(); и отново в new Fragment_1();. Съобщението за затъмнение е Type mismatch: cannot convert from Fragment_1 to Fragment.

Това е Fragment_1.java:

package com.rufflez.absnavdrawer;

import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.webkit.WebChromeClient;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;

public class Fragment_1 extends FragmentActivity{
WebView webview;
private String url;
ProgressBar pd = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);        
    setContentView(R.layout.activity_main);


  //  pd = (ProgressBar) findViewById(R.id.web_view_progress_bar);

  //  webview = (WebView) findViewById(R.id.WebView);       

    webview.setWebChromeClient(new WebChromeClient() {
        @Override
        public void onProgressChanged(WebView view, int progress) {
           if(progress < 100 && pd.getVisibility() == View.GONE){
               pd.setVisibility(View.VISIBLE);
           }
           pd.setProgress(progress);
           if(progress == 100) {
              pd.setVisibility(View.GONE);
           }
        }
    });

    webview.setWebViewClient(new WebViewClient() {
        @Override
        public boolean shouldOverrideUrlLoading(WebView view, String url){
            // do your handling codes here, which url is the requested url
            // probably you need to open that url rather than redirect:
             if (url.startsWith("tel:")) {
                 startActivity(new Intent(Intent.ACTION_DIAL, Uri.parse(url)));
             } else if (url.startsWith("mailto:")) {
                 url = url.replaceFirst("mailto:", "");
                 url = url.trim();
                 Intent i = new Intent(Intent.ACTION_SEND);
                 i.setType("plain/text").putExtra(Intent.EXTRA_EMAIL, new String[]{url});
                 startActivity(i);



             } else {
                 view.loadUrl(url);
             }
             return true;
             // then it is not handled by default action
       }
    });


    webview.loadUrl("file:///android_asset/about.html");
}



@Override
public void onBackPressed()
{
    if(webview.canGoBack())
        webview.goBack();
    else
        super.onBackPressed();
}

public void setUrl(String url) {
    this.url = url;
}

public String getUrl() {
    return url;
}
}