使用Treeview控件，有错误，请帮忙。

Public Sub MakeTree(tvwX As TreeView)
     Dim nodX As Node
     Dim sNodeKey As String
     Dim sRelative As String
     Dim MsgText As String
     txtSQL = "select * from 系部"
     Set mrc = ExecuteSQL(txtSQL, MsgText)
     '添加系
     Do Until mrc.EOF
         sNodeKey = "X" & mrc("系部代码").Value
         Set nodX = tvwX.Nodes.Add(, , sNodeKey, mrc("系部名称").Value)
         nodX.Tag = "系"
         mrc.MoveNext
     Loop
     mrc.Close
     txtSQL = "select * from 专业"
     Set mrc = ExecuteSQL(txtSQL, MsgText)
     '添加专业
     Do Until mrc.EOF
         sNodeKey = "X" & mrc("专业代码").Value
         sRelative = Mid$(sNodeKey, 1, 3)
         Set nodX = tvwX.Nodes.Add(, , sNodeKey, mrc("专业名称").Value)
         nodX.Tag = "专业"
         mrc.MoveNext
     Loop
     mrc.Close
     txtSQL = "select * from 班级"
     Set mrc = ExecuteSQL(txtSQL, MsgText)
     '添加班级
     Do Until mrc.EOF
         sNodeKey = "X" & mrc("班号").Value
         sRelative = Mid$(sNodeKey, 1, 5)
         Set nodX = tvwX.Nodes.Add(, , sNodeKey, mrc("班级名称").Value)
         nodX.Tag = "班级"
         mrc.MoveNext
     Loop
     mrc.Close
     Set tvwX.SelectedItem = tvwX.Nodes(1)
     Set mrc = Nothing
     Set nodX = Nothing
   End Sub
Private Sub Form_Load()
   Call comboAddItem(Combo2, "班级", 0)
  Call comboAddItem(Combo3, "系部", 0)
  Call MakeTree(TreeView1)
End Sub
代码是这样写的，可是显示的时候不分层啊，老是一下子全部显示出来了！请大家帮忙，

[ 本帖最后由 你好毒 于 2010-12-14 16:45 编辑 ]