ดึงข้อมูลจากฐาน access ลง combobox และให้ textbox แสดงค่าตามที่เลือก combobox ครับ

Private Sub ComboBox1_Click(sender As Object, e As EventArgs) Handles ComboBox1.Click
        Dim sql As String
        sql = "SELECT * FROM ServiceCharge"
        Dim da As New OleDbDataAdapter(sql, cn)
        Dim ds As New DataSet
        da.Fill(ds, "ServiceCharge")
        ComboBox1.DataSource = ds.Tables("ServiceCharge")
        ComboBox1.DisplayMember = "ServiceCharge"
        ComboBox1.ValueMember = "ServiceCharge"

        Dim sql2 As String
        sql2 = "SELECT * FROM ServiceCharge where ServiceCharge = '" & CStr(ComboBox1.Text) & "'"
        Dim da2 As New OleDbDataAdapter(sql2, cn)
        Dim ds2 As New DataSet
        da2.Fill(ds2, "ServiceCharge")
        TextBox4.Text = CStr(ds2.Tables("ServiceCharge").Rows(0).Item("Price"))
    End Sub

 Private Sub frmDailyWork_Load(sender As Object, e As EventArgs) Handles MyBase.Load

        Me.CenterToScreen()
        Dim strPath As String = Application.StartupPath
        strPath = strPath.ToLower()
        Dim strConn As String = "Provider=Microsoft.ACE.OLEDB.12.0; Data Source=|DataDirectory|data\Database.accdb; Persist Security Info = false;"

        Try
            ' เปิดการเชื่อมต่อไฟล์ฐานข้อมูล
            Conn = New OleDb.OleDbConnection(strConn)
            Conn.Open()
            '// โหลดรายการจังหวัดเข้ามาก่อน
            Call LoadProvice()
        Catch ex As Exception
            MsgBox(ex.Message)
            Application.Exit()
        End Try

    End Sub

    Sub LoadProvice()
        ' DISTINCT คือ หากชื่อรายการมันซ้ำ ต้องตัดให้เหลือเพียงรายการเดียว
        Statement =
            " SELECT * " &
            " From ServiceCharge "
        cmd = New OleDbCommand(Statement, Conn)
        dr = cmd.ExecuteReader
        While dr.Read()
            ComboBox1.Items.Add(dr.Item("ServiceCharge").ToString)
        End While
        dr.Close()
        cmd.Dispose()
    End Sub

 Private Sub ComboBox1_SelectedValueChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedValueChanged
        TextBox4.Clear()
        TextBox4.Text = ""
        Statement =
            " SELECT * " &
            " From ServiceCharge  " &
            " WHERE " &
            " ServiceCharge = " & "'" & ComboBox1.Text & "'" &
            " ORDER BY id "
        cmd = New OleDbCommand(Statement, Conn)
        dr = cmd.ExecuteReader
        While dr.Read()
            TextBox4.Text = dr.Item("Price").ToString
        End While
        dr.Close()
        cmd.Dispose()
    End Sub