主题：目录树节点问题

老师目录树不可以设置4级的吗，，，我设计的4级，第一级的名称和第2级的一样的

Dim tr As WinForm.TreeView
Dim nd As WinForm.TreeNode
tr = e.Form.Controls("TreeView1")
nd = tr.SelectedNode
If nd IsNot Nothing Then
    If nd.Level = 3 Then
        MessageBox.Show("最多允许三层节点!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information)
    Else
        Dim dr As DataRow = DataTables("授权").AddNew
        If nd.Level = 0 Then
            dr("分组名") = nd.Text
            dr("表名") = "新节点"
        ElseIf nd.Level = 1 Then
            dr("分组名") = nd.ParentNode.Text
            dr("表名") = nd.text
            dr("列名") = "新节点"
        ElseIf nd.Level = 2 Then
            dr("分组名") = nd.ParentNode.Text
            dr("表名") = nd.ParentNode.Text
            dr("列名") = nd.text
            dr("导航按钮") = "新节点"
        End If
        nd = nd.Nodes.Add("新节点")
        tr.SelectedNode = nd
        tr.Select()
        tr.BeginEdit()
    End If
End If
DataTables("授权").Save