dropdownlist asp.net เจ้า selected value ไม่ทำงานครับ

Private Sub Province()
        Dim sqlProvince As String
        sqlProvince = "SELECT PROVINCEID,PROVINCENAME FROM PROVINCE "
        Comm = New OracleCommand(sqlProvince, Conn)
        Dr = Comm.ExecuteReader()
        DtProvince = New DataTable
        DtProvince.Load(Dr)
        With cboProvince
            .DataSource = DtProvince
            .DataTextField = "PROVINCENAME"
            .DataValueField = "PROVINCEID"
            .DataBind()
        End With
End Sub

		myDDL1.SelectedIndex = myDDL1.Items.IndexOf(myDDL1.Items.FindByValue("TH"))  '*** By DataValueField ***'
		'myDDL1.SelectedIndex = myDDL1.Items.IndexOf(myDDL1.Items.FindByText("Thailand"))  '*** By DataTextField ***'