BING贴图图层和引脚:如何在多边形图层上绘制引脚

i有两个var as，

map = new Microsoft.Maps.Map(document.getElementById("mapDiv"), {
        showMapTypeSelector:false,
        showScalebar:false,
        enableSearchLogo:false,
        showDashboard:true,
        credentials:"Aku0L3I-4aBqUL0zUWpJYNIp-vppMK2h",
        mapTypeId:Microsoft.Maps.MapTypeId.road, 
        zoom:4,
        center:new Microsoft.Maps.Location(38.3466110000000029,-77.0653559999999942)
    });

这个Map var用来在我的bing地图上绘制多边形。

greenLayer = new ClusteredEntityCollection(map, {
        singlePinCallback: createPin,
        clusteredPinCallback: createClusteredPin,
        clusterPlacementType: 2,
        clusteringEnabled: true,
        visible: true,
        gridSize: 50
    });

这个绿层是用来在bing地图上画大头针的。

运行时，

the polygon is up and the pins is down.
i need to draw polygon down and pins up.

如何在bing映射中执行CCD_ 1。