Does not google maps load me with the location?

I am developing a bus application where according to the user's location it tells me that bus is closer to my position to be able to get to X place but my main problem is that I can not get the app to detect my location.

On the map:

import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import static android.Manifest.permission.ACCESS_FINE_LOCATION;
import com.google.android.gms.maps.CameraUpdate;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.BitmapDescriptorFactory;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Marker;
import com.google.android.gms.maps.model.MarkerOptions;

public class MapaComoLLegar extends FragmentActivity implements OnMapReadyCallback {

private GoogleMap mMap;
private Marker marcador;
double lat = 0.0;
double lng = 0.0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_mapa_como_llegar);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
}


@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    miUbicacion();

}

private void agreagarMarcador(double lat, double lng) {
    LatLng coordenadas = new LatLng(lat, lng);
    CameraUpdate miUbicacion = CameraUpdateFactory.newLatLngZoom(coordenadas, 16);
    if (marcador != null) marcador.remove();
    marcador = mMap.addMarker(new MarkerOptions()
            .position(coordenadas)
            .title("Mi posicion actual")
            .icon(BitmapDescriptorFactory.fromResource(R.mipmap.ic_launcher)));
    mMap.animateCamera(miUbicacion);
}

private void actualizarUbicacion(Location location) {
    if (location != null) {
        lat = location.getLatitude();
        lng = location.getLongitude();
        agreagarMarcador(lat, lng);
    }
}

LocationListener locListener = new LocationListener() {
    @Override
    public void onLocationChanged(Location location) {
        actualizarUbicacion(location);
    }

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

    }

    @Override
    public void onProviderEnabled(String provider) {

    }

    @Override
    public void onProviderDisabled(String provider) {

    }
};
private static final int PETICION_PERMISO_LOCALIZACION = 101;
    private void miUbicacion() {
    if (ActivityCompat.checkSelfPermission(this, 
Manifest.permission.ACCESS_FINE_LOCATION) != 
PackageManager.PERMISSION_GRANTED && 
ActivityCompat.checkSelfPermission(this, 
Manifest.permission.ACCESS_COARSE_LOCATION) != 
PackageManager.PERMISSION_GRANTED) {
      //  ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION},
        //        PETICION_PERMISO_LOCALIZACION);
        LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
        Location location = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
        actualizarUbicacion(location);
        locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 15000, 0, locListener);
    }else return;

    }
}

I need help to know that it is wrong or because it does not load, when compiling it only stays on the map without showing the marker or moving the camera.