请教：绘画多边形的问题

源代码如下，但怎么也看不到那个多边形，恳请高手指点。

Option Explicit
Dim dc As New MapObjects2.DataConnection
Dim lyr As New MapObjects2.MapLayer




Private Sub Form_Load()

    
               dc.Database = "[ARC]D:\agrgis\maps\gsfxdx"
               If Not dc.Connect Then End
               Set lyr.GeoDataset = dc.FindGeoDataset("dx0101.pat")
                  Map1.Layers.Add lyr
End Sub

Private Sub Map1_AfterLayerDraw(ByVal index As Integer, ByVal canceled As Boolean, ByVal hDC As stdole.OLE_HANDLE)
Dim sym As New MapObjects2.Symbol
Dim pPolygon As New MapObjects2.Polygon
Dim pPoints As New MapObjects2.Points, pPt As New MapObjects2.Point

pPt.Set 100, 100

pPoints.Add pPt

pPt.Set 400, 100
pPoints.Add pPt

pPt.Set 250, 400
pPoints.Add pPt

pPt.Set 100, 100
pPoints.Add pPt

pPolygon.Parts.Add pPoints
 


sym.SymbolType = moFillSymbol
sym.Style = moDiagonalCrossFill
sym.Color = moRed

Map1.DrawShape pPolygon, sym
Map1.Refresh

End Sub

Private Sub Map1_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
 
  Map1.Refresh

End Sub