LocationManager network_provider troubles

public class MyLocationTracker extends Service{
 
    private static final long MINIMUM_DISTANCE_CHANGE_FOR_UPDATES = 1000;
    private static final long MINIMUM_TIME_BETWEEN_UPDATES = 60000;
 
    protected LocationManager locationManager;
    protected LocationListener listener;
 
    @Override
    public void onCreate(){
 
        super.onCreate();
        Toast.makeText(this, "Location Tracking Service started", Toast.LENGTH_LONG).show();
        listener=new MyLocationListener();
        locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER,
                MINIMUM_TIME_BETWEEN_UPDATES,
                MINIMUM_DISTANCE_CHANGE_FOR_UPDATES, listener);
        Location location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
        if (location != null) {
            String message = String.format(
                    "Current Location \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude());
            Toast.makeText(MyLocationTracker.this, message, Toast.LENGTH_LONG).show();
        }
        }
 
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
 
    @Override
    public void onDestroy(){
        Toast.makeText(this, "Location Tracking Service stopped", Toast.LENGTH_LONG).show();
        locationManager.removeUpdates(listener);
        super.onDestroy();
    }
    private class MyLocationListener implements LocationListener{
 
        @Override
        public void onLocationChanged(Location location) {
            String message = String.format(
                    "New Location \n Longitude: %1$s \n Latitude: %2$s",
                    location.getLongitude(), location.getLatitude());
            Toast.makeText(MyLocationTracker.this, message, Toast.LENGTH_LONG).show();
 
        }
 
        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) {
            Toast.makeText(MyLocationTracker.this, "Provider status changed", Toast.LENGTH_LONG).show();
 
        }
 
        @Override
        public void onProviderEnabled(String s) {
            Toast.makeText(MyLocationTracker.this,
                    "Provider enabled by the user. Tracking turned on", Toast.LENGTH_LONG).show();
 
        }
 
        @Override
        public void onProviderDisabled(String s) {
            Toast.makeText(MyLocationTracker.this,
                    "Provider disabled by the user. Tracking turned of", Toast.LENGTH_LONG).show();
 
        }
    }
}