求助mapobject 画方里网的问题

<P>Private Sub fangli_Click()<BR>   Dim pt As New MapObjects2.Point<BR>   Dim line As New MapObjects2.line<BR>   Dim pts As New MapObjects2.Points<BR>   Dim i As Integer<BR>   For i = 1 To CInt(Map1.Width / 100)<BR>     pt.x = Map1.Left + i * 100<BR>     pt.y = Map1.Extent.Top<BR>     pts.Add pt<BR>     pt.x = Map1.Left + i * 100<BR>     pt.y = Map1.Extent.Bottom<BR>     pts.Add pt<BR>     line.Parts.Add pts<BR>     Map1.TrackingLayer.AddEvent line, 0<BR>   Next<BR>   For i = 1 To CInt(Map1.Height / 100)<BR>     pt.x = Map1.Extent.Left<BR>     pt.y = Map1.Extent.Top - i * 100<BR>     pts.Add pt<BR>     pt.x = Map1.Extent.Right<BR>     pt.y = Map1.Extent.Top - i * 100<BR>     pts.Add pt<BR>     line.Parts.Add pts<BR>     Map1.TrackingLayer.AddEvent line, 0<BR>    Next<BR>    Map1.Refresh<BR>    <BR>End Sub</P>
<P>请问高手们，这样画方里网错在哪啊？每次运行都死在那。</P>