treeview node派生的问题

[胡楮智]

'1 自定义treenode
Public Class myTreeNode
Inherits System.Windows.Forms.TreeNode

Public iNowLevel As Int16 '当前节点的层数
Public iNowNo As Integer '当前节点的序号　
Public iupNo As Integer '当前节点的上级序号　
Public sCode As String '当前节点的编号
Public sName As String '当前节点的名称
Sub New(ByVal sCode As String, ByVal iNowNo As Integer, ByVal sName As String, ByVal iupNo As Integer, ByVal iNowLevel As Int16)
MyBase.New()
Me.Text = sName
Me.sCode = sCode
Me.iNowNo = iNowNo
Me.sName = sName
Me.iNowLevel = iNowLevel
End Sub

End Class
'2 将自定义treenode 加入到treeview的nodes中

'3 希望使用自定义treenode的属性，写了下面的代码
'下面是窗口中treeview控件的事件代码：
Private Sub Trv_AfterSelect(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles Trv.AfterSelect
Dim myn As myTreeNode
myn = CType(e.Node, myTreeNode)
'myn = e.Node
Dim sstr As String
sstr = myn.sName
End Sub
End Class


问题是：ctype()转换无效！无法转换！
也就是下面的语句无法执行：
myn = CType(e.Node, myTreeNode)

[myvbnet]

下面的例子有你这种情况：
http://images.csdn.net/20040906/开发高手第九期源代码.rar