请问转换坐后，GraphicsOverlay不显示是为什么

创建点的时候，换成屏幕点击后的点就可以显示，但如下代码图层不显示
SimpleMarkerSymbol simpleMarkerSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbol.Style.CIRCLE, Color.GREEN, 20);
 GraphicsOverlay graphicsOverlay = new GraphicsOverlay(); 
Point point = new Point(102.6542,25.0945, SystemManager.mapView.getSpatialReference() ); Graphic graphic = new Graphic(point, simpleMarkerSymbol); graphicsOverlay.getGraphics().add(graphic); SystemManager.mapView.getGraphicsOverlays().add(graphicsOverlay);