Android สวัสดีครับ อยากสอบถามเกี่ยวกับ การ Get ค่า Latitude และ Longitude ไม่ได้ครับ

package com.wittawat.locationdemo;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import android.location.Location;
import android.support.v7.app.ActionBarActivity;
import android.util.Log;
import android.widget.TextView;
import android.widget.Toast;

import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationServices;



public class MainActivity extends ActionBarActivity
    implements GoogleApiClient.ConnectionCallbacks,
    GoogleApiClient.OnConnectionFailedListener{

    private static final String TAG = "LocationDemo";

    private GoogleApiClient mGoogleApiClient;
    private TextView mLatitudeTextView;
    private TextView mLongitudeTextView;




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

        // อ้างอิงไปยังเท็กซ์วิวทั้งสอง
        mLatitudeTextView = (TextView) findViewById(R.id.latitude);
        mLongitudeTextView=(TextView)findViewById(R.id.longitude);

        // สร้างออบเจ็ค GoogleApiClient
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @Override
    public void onConnected(Bundle bundle){
        Location lastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);

        if (lastLocation != null){
            mLatitudeTextView.setText(String.valueOf(lastLocation.getLatitude()));
            mLongitudeTextView.setText(String.valueOf(lastLocation.getLongitude()));
        }else {
            Toast.makeText(this,"ไม่สามรถระบุตำแหน่งได้",Toast.LENGTH_LONG).show();
        }
    }

    @Override
    public void onConnectionSuspended(int i){
        Log.i(TAG,"Connection suspended");
        mGoogleApiClient.connect();
    }

    @Override
    public void onConnectionFailed(ConnectionResult connectionResult){
        Log.i(TAG,"Connection failed: error code = "
        + connectionResult.getErrorCode());
    }

    @Override
    public void onStart(){
        super.onStart();
        mGoogleApiClient.connect();
    }

    @Override
    public  void onStop(){
        if (mGoogleApiClient.isConnected()){
            mGoogleApiClient.disconnect();
        }
        super.onStop();
    }
}