无法在Android中获取当前位置的当前纬度和经度

我使用下面的代码来获取用户的当前位置。此代码在emulator中工作，但当我在移动设备中使用此应用程序时，它无法给出当前的纬度和经度。 我在android清单文件中使用此代码

请给我解决方案。。。我的代码在下面

public class MenuPage extends Activity{



@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.menupage);


     LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
     LocationListener locListener = new MyLocationListener();
     locationManager.requestLocationUpdates( LocationManager.GPS_PROVIDER, 0, 0, locListener);



}

/*获取用户当前位置的MyLocationListener类的开始*/

public class MyLocationListener implements LocationListener

{

    @Override

    public void onLocationChanged(Location crurrentLocation)

    {
          Log.v("WHERE ","onLocationChanged()");
          crurrentLocation.getLatitude(); // get current latitude
          crurrentLocation.getLongitude(); // get current longitude
           longitude=crurrentLocation.getLongitude();
           latitude=  crurrentLocation.getLatitude();

           Log.v("WHERE ","onLocationChanged()  Latitude="+latitude);   
           Log.v("WHERE ","onLocationChanged()  Longitude="+longitude); 
            Toast.makeText(getApplicationContext(),"Latitud="+crurrentLocation.getLatitude(),Toast.LENGTH_SHORT).show(); 
            Toast.makeText(getApplicationContext(),"Longitud="+crurrentLocation.getLongitude(),Toast.LENGTH_SHORT).show();

            send_current_location = new Send_Current_location_ToServer();
      // Send current location to server
            String server_message =  send_current_location.sendData(userid,latitude,longitude);    
         //   String text ="My current location is: " + "Latitud = " + crurrentLocation.getLatitude() + "Longitud = " + crurrentLocation.getLongitude();
         //   Toast.makeText(getApplicationContext(),text,Toast.LENGTH_SHORT).show();

    }

    @Override

    public void onProviderDisabled(String provider)

    {
          Log.v("WHERE ","onProviderDisabled()");
    Toast.makeText( getApplicationContext(),"Gps Disabled",Toast.LENGTH_SHORT ).show();

    }

    @Override

    public void onProviderEnabled(String provider)

    {
         Log.v("WHERE ","onProviderEnabled()");

    Toast.makeText( getApplicationContext(),"Gps Enabled",Toast.LENGTH_SHORT).show();

    }

    @Override

    public void onStatusChanged(String provider, int status, Bundle extras)

    {
         Log.v("WHERE ","onStatusChanged()");
    }

}/* End of Class MyLocationListener */

---

}

2.3 emulator中有一个关于位置服务的错误。尝试更改为2.1以测试代码

有关定位服务的更多信息，请使用

有关错误的状态，请参阅