Синхронизация меток на google карте с помощью Firebase

Должен срабатывать метод

@Override
        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
            LatLng sc = dataSnapshot.getValue(LatLng.class);
            MarkerOptions markerOptions = new MarkerOptions();
            markerOptions.position(sc);
            markerOptions.title(sc.latitude + " : "+ sc.longitude);
            googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(sc, 10));
            googleMap.addMarker(markerOptions);
        }

но метка на 2 телефоне не появляется.

public class DashboardFragment extends Fragment implements View.OnClickListener { static class Item{ LatLng cor1;

    public Item(LatLng cor1) {
        this.cor1 = cor1;

    }

    public Item() {
    }
}


MapView mMapView;
private GoogleMap googleMap;
private FirebaseDatabase database = FirebaseDatabase.getInstance();
private DatabaseReference myRef = database.getReference("items");



@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_dashboard, container, false);
    mMapView = (MapView) rootView.findViewById(R.id.mapView);
    mMapView.onCreate(savedInstanceState);
    mMapView.onResume();

    try {
        MapsInitializer.initialize(getActivity().getApplicationContext());
    } catch (Exception e) {
        e.printStackTrace();
    }

    mMapView.getMapAsync(new OnMapReadyCallback() {
        @Override
        public void onMapReady(final GoogleMap gmap) {
            googleMap = gmap;
            LatLng vietnam = new LatLng(48.707103, 44.516939);
            googleMap.moveCamera(CameraUpdateFactory.newLatLng(vietnam));
            googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(vietnam, 10));

            googleMap.setOnMapClickListener(new GoogleMap.OnMapClickListener() {
                @Override
                public void onMapClick(final LatLng latLng) {
                    MarkerOptions markerOptions = new MarkerOptions();
                    markerOptions.position(latLng);
                    markerOptions.title(latLng.latitude + " : "+ latLng.longitude);
                    googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLng, 10));
                    googleMap.addMarker(markerOptions);
                    DialogFrag dialog = new DialogFrag();
                    assert getFragmentManager() != null;
                    dialog.show(getFragmentManager(), "custom");
                    FirebaseDatabase.getInstance().getReference().push().setValue(latLng);
                }
            });
        }
    });
    myRef.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {
            LatLng sc = dataSnapshot.getValue(LatLng.class);
            MarkerOptions markerOptions = new MarkerOptions();
            markerOptions.position(sc);
            markerOptions.title(sc.latitude + " : "+ sc.longitude);
            googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(sc, 10));
            googleMap.addMarker(markerOptions);
        }

        @Override
        public void onChildChanged(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onChildRemoved(@NonNull DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(@NonNull DataSnapshot dataSnapshot, @Nullable String s) {

        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

    return rootView;
}




@Override
public void onResume() {
    super.onResume();
    mMapView.onResume();
}

@Override
public void onPause() {
    super.onPause();
    mMapView.onPause();
}

@Override
public void onDestroy() {
    super.onDestroy();
    mMapView.onDestroy();
}

@Override
public void onLowMemory() {
    super.onLowMemory();
    mMapView.onLowMemory();
}

@Override
public void onClick(View v) {
}

}