In android map shows a blue screen instead of a map

hello everyone I have a code to display two places on the map with a marker, but it shows only a marker, and only a blue screen is displayed on the map. I am running on a mobile not an emulator.

my code

 public class HelloGoogleMaps3 extends MapActivity {
private MapView map=null;
private MyLocationOverlay me=null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    map=(MapView)findViewById(R.id.map);

    map.getController().setCenter(getPoint
            (40.76793169992044,-173.98180484771729));
    map.getController().setZoom(17);
    map.setBuiltInZoomControls(true);

    Drawable marker=getResources().getDrawable(R.drawable.marker);

    marker.setBounds(0, 0, marker.getIntrinsicWidth(),
                    marker.getIntrinsicHeight());

    map.getOverlays().add(new SitesOverlay(marker));

    me=new MyLocationOverlay(this, map);
    map.getOverlays().add(me);
}

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

    me.enableCompass();
}       

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

    me.disableCompass();
}       

@Override
protected boolean isRouteDisplayed() {
    return(false);
}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_S) {
        map.setSatellite(!map.isSatellite());
        return(true);
    }
    else if (keyCode == KeyEvent.KEYCODE_Z) {
        map.displayZoomControls(true);
        return(true);
    }

    return(super.onKeyDown(keyCode, event));
}

private GeoPoint getPoint(double lat, double lon) {
    return(new GeoPoint((int)(lat*1000000.0),
                        (int)(lon*1000000.0)));
}

private class SitesOverlay extends ItemizedOverlay<OverlayItem> {
    private List<OverlayItem> items=new ArrayList<OverlayItem>();
    private Drawable marker=null;

    public SitesOverlay(Drawable marker) {
        super(marker);
        this.marker=marker;

        items.add(new OverlayItem(getPoint
                (40.748963847316034,-173.96807193756104),
                            "UN", "United Nations"));
        items.add(new OverlayItem(getPoint
                (40.76866299974387,-173.98268461227417),
                            "Lincoln Center",
                            "Home of Jazz at Lincoln Center"));
        items.add(new OverlayItem(getPoint
                (40.765136435316755,-173.97989511489868),
                            "Carnegie Hall",
                    "Where you go with practice, practice, practice"));
        items.add(new OverlayItem(getPoint
                (40.70686417491799,-174.01572942733765),
                            "The Downtown Club",
                    "Original home of the Heisman Trophy"));

        populate();
    }

    @Override
    protected OverlayItem createItem(int i) {
        return(items.get(i));
    }

    @Override
    public void draw(Canvas canvas, MapView mapView,
                                    boolean shadow) {
        super.draw(canvas, mapView, shadow);

        boundCenterBottom(marker);
    }

    @Override
    protected boolean onTap(int i) {
        Toast.makeText(HelloGoogleMaps3.this,
                            items.get(i).getSnippet(),
                            Toast.LENGTH_SHORT).show();

        return(true);
    }

    @Override
    public int size() {
        return(items.size());
    }
}

}