VB.NET Load XML ไม่ขึ้นภาษาไทย ผมเขียนโค้ด แล้วมันขึ้นไม่ใช่ภาษาไทย ช่วยดูหน่อยคับผิดที่ตรงไหน

 Private Sub loadEvent()
        Dim xdocaa As XDocument = XDocument.Load("C:\xml\login2.xml")
        Dim sb As New StringBuilder

        'asuming you have more than 1 plugin in the xml file
        Dim Subjet = From x In xdocaa.Root.<subject> Where x.@name = "Principles of Programming Languages " And x.<subsec>.Value = "800"
        For Each el As XElement In Subjet.<all_topic>.<topic>    'xdocaa.Root.Elements.<all_topic>.<topic>
            sb.AppendFormat("Topic : " & el.<topicname>.Value & Environment.NewLine & _
                            "Detail : " & el.<topicdetail>.Value & Environment.NewLine & _
                            "Teacher : " & el.<topicadviser>.Value & Environment.NewLine & _
                            "Date : " & el.<topicdate>.Value & Environment.NewLine & _
                            "--------------------------------------------------" & Environment.NewLine & Environment.NewLine)
        Next
        'MessageBox.Show(sb.ToString)
        txtlogin.Text = sb.ToString
    End Sub

<?xml version='1.0' encoding='TIS-620'?>
<subjects>
	<subject name = "Principles of Programming Languages ">
		<subsec>800</subsec>
		<subdate>F-13-16</subdate>
		<all_topic>
			<topic>
				                            <topicname>เทสข้อความ</topicname>
				<topicdetail>ข้อความ</topicdetail>
				<topictype>ข้อความ</topictype>
				<topicdate>2011-12-18 00:00:00</topicdate>
				<topicadviser>ข้อความ</topicadviser>
			</topic>
			<topic>
				<topicname>เทสข้อความ</topicname>
				<topicdetail>ข้อความ</topicdetail>
				<topictype>ข้อความ</topictype>
				<topicdate>2012-02-01 20:36:09</topicdate>
				<topicadviser>ข้อความ</topicadviser>
			</topic>
		</all_topic>
	</subject>
</subjects>