I am trying use google maps by JSNI,Following code snippet throws out an exception:

com.google.gwt.core.client.JavaScriptException: (TypeError): $wnd.google.maps.LatLng is not a constructor at com.google.gwt.dev.shell.BrowserChannelServer.invokeJavascript(BrowserChannelServer.java:248)
.....

can anybody help me to point out what's wrong here?
---------------------------------------------------

```
@Override
public void init(final Point center, final int zl)
{
    ScriptInjector
            .fromUrl(   "http://maps.googleapis.com/maps/api/js?sensor=false&language="
                                + Cookies.getCookie(LocaleInfo.getLocaleCookieName()))
            .setWindow(ScriptInjector.TOP_WINDOW).setCallback(new Callback<Void, Exception>()
            {
                public void onFailure(Exception reason)
                {
                    // I18N
                    Window.alert("load google maps api failed,all map function will not work.");
                }

                public void onSuccess(Void result)
                {
                    map = initMap(getElement(), center.getLatitude(), center.getLongitude(), zoomLevel = zl);
                }
            }).inject();
}

native JavaScriptObject initMap(Element canvas, double latitude, double longitude, int zoomLevel) /*-{
    return new $wnd.google.maps.Map(canvas, {
        zoom : zoomLevel,
        center : new $wnd.google.maps.LatLng(latitude, longitude),
        mapTypeId : $wnd.google.maps.MapTypeId.ROADMAP
    });
}-*/;

```