请问下树型控件取数据表的数值后的有关问题

'改代码是由VB6转的,现在运行没有提示错误,但不知为何TreeView控件却显示一片空白.请教下是什么原因呢.

Private Sub Form1_Load(ByVal eventSender As System.Object, ByVal eventArgs As System.EventArgs) Handles MyBase.Load
        Call addTVW(Me.TreeView1)
    End Sub
    Public Sub addTVW(ByVal TVW As System.Windows.Forms.TreeView)
        Dim rs As Object '添加树视过程
        Dim db As ADODB.Connection
        db = New ADODB.Connection
        db.CursorLocation = ADODB.CursorLocationEnum.adUseClient

        db.Open("PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=" & My.Application.Info.DirectoryPath & "\2.mdb" & ";") '注意此处的文件名

        Dim sql As String
        sql = "select * from 表1" '注意此处的SQL语句

        rs = New ADODB.Recordset

        rs.Open(sql, db, ADODB.CursorTypeEnum.adOpenStatic, ADODB.LockTypeEnum.adLockOptimistic)



        On Error Resume Next


        Dim a As String

        Do While Not rs.EOF '循环读取数据
            Err.Clear()
            a = TVW.Nodes.Item("A" & rs.Fields("名称")).Text
            If Err.Number <> 0 Then
                TVW.Nodes.Add("A" & rs.Fields("名称"), rs.Fields("名称"))
                If Len(rs.Fields("种类")) > 0 Then TVW.Nodes.Find("A" & rs.Fields("名称"), True)(0).Nodes.Add("B" & rs.Fields("种类"), rs.Fields("种类"))
                Err.Clear()

            End If


            rs.MoveNext()
        Loop


    End Sub

        Dim con As OleDb.OleDbConnection
        Dim cstring As String = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=" & My.Application.Info.DirectoryPath & "\2.mdb"

        Dim sql As String = "select 名称,种类,产地 from 表1" '名称,种类,产地，，，为'myreader(0)'myreader(1)'myreader(2)
        Dim sales As DataSet = New DataSet
        Dim cmd As OleDb.OleDbCommand
        con = New OleDb.OleDbConnection(cstring)
        'If di1 = " " And di2 = " " Then
        '    MessageBox.Show("请输入正确信息 ")
        'Else
        con.Open()
        cmd = New OleDb.OleDbCommand(sql, con)
        cmd.CommandText() = sql


        Dim myreader As OleDb.OleDbDataReader = cmd.ExecuteReader
        While myreader.Read

            a = TVW.Nodes.Item("A" & myreader(0)) 'myreader(0)就=rs.Fields("名称")
            If Err.Number <> 0 Then
                TVW.Nodes.Add("A" & myreader(0), myreader(0))
                If Len(myreader(1)) > 0 Then TVW.Nodes.Find("A" & myreader(0), True)(0).Nodes.Add("B" & myreader(1), myreader(1))

            End If



        End While
        con.Close()