选择显示点要素

这段是实现map控件中选择一个给定层上点要素的代码，运行程序后点击一个点要素没反映。大家帮我看下问题出在哪里<BR>     <BR>        Dim pmap As IMap<BR>        Dim pview As IActiveView<BR>        pmap =AxMapControl1.Map<BR>        pview = pmap<BR>        Dim play As IFeatureLayer<BR>        Dim ppoint As IPoint<BR>        ppoint = New Point<BR>        ppoint.PutCoords(e.mapX, e.mapY)<BR>        play = pmap.Layer(3)<BR>        <BR>       <BR>        Dim psele As ISelectionEnvironment<BR>        psele = New SelectionEnvironment<BR>        psele.PointSelectionMethod = 4<BR>        pmap.SelectFeature(play, ppoint)<BR>        pview.Refresh()