รันเลข ID อัตโนมัติจาก Access แต่ไม่ได้สักทีขอเทพแก้ให้ทีครับ

Private Sub AutoCode()
        Cm = New OleDbCommand("Select Max(ProductID)As ProCode From Product", Cn)
        Dr.Read()
        If NOT dr.HasRow Then
            TextBox1.Text = "0001"
        Else
            Procode = Dr("Procode") + 1
            Select Case Procode
                Case Is < 10
                    TextBox1.Text = "000" & Procode
                Case Is < 100
                    TextBox1.Text = "00" & Procode
                Case Is < 1000
                    TextBox1.Text = "0" & Procode
                Case Is < 10000
                    TextBox1.Text = Procode
            End Select
        End If

Cm = New OleDbCommand("select max (ProductID)As maxcode From Product", Cn)
        Dr = Cm.ExecuteReader
        Dr.Read()
        If Dr("Maxcode") Is DBNull.Value Then
            TextBox1.Text = "0001"
        Else
            Procode = Dr("Maxcode") + 1
            Select Case Procode
                Case Is < 10
                    TextBox1.Text = "000" & Procode
                Case Is < 100
                    TextBox1.Text = "00" & Procode
                Case Is < 1000
                    TextBox1.Text = "0" & Procode
                Case Is < 10000
                    TextBox1.Text = Procode
            End Select

        End If

    End Sub