problem accessing with DTD data in xml

[zmerzed]

I am having a problem accessing with DTD data in xml.

Imports System
Imports System.Xml


Module Module1

    Sub Main()
   
        Using reader As XmlReader = XmlReader.Create("00000002.xml")
            While reader.Read()
                ' Check for start elements.
                If reader.IsStartElement() Then

                    ' See if perls element or article element.
                    If reader.Name = "result" Then
                        Console.WriteLine("Start <result> element.")

                    ElseIf reader.Name = "sample" Then
                        Console.WriteLine("Start <sample> element.")
                        ' Get name attribute.
                        Dim attribute As String = reader("samplenumber")
                        If attribute IsNot Nothing Then
                            Console.WriteLine("  Has attribute name: {0}", attribute)
                        End If

                        ' Text data.
                        If reader.Read() Then
                            Console.WriteLine("  Text node: {0}", reader.Value.Trim())
                        End If
                    End If

                End If
            End While
        End Using
      
    End Sub
End Module

in xml file

<?xml version="1.0" standalone="no"?>
<!DOCTYPE result SYSTEM "result.dtd">
<result>
<sample sampleid="1" samplenumber="RLG 512" applname="Starter" n_constituent="12">
<datestart year="2012" month="6" date="19" hour="7" minute="27" second="2"/>
<datestop year="2012" month="6" date="19" hour="7" minute="27" second="32"/>
<constituent id="1" name="Brix" value="     14.04" GH="      1.69" NH="      1.09"/>
<constituent id="2" name="Pol" value="     10.15" GH="      1.69" NH="      1.09"/>
<constituent id="19" name="Trash" value="     28.66" GH="      0.00" NH="6182057154624353400000000000000000.00"/>
<constituent id="20" name="Fibre" value="      9.52" GH="      1.69" NH="      1.09"/>
<constituent id="21" name="Ash" value="     -0.63" GH="      1.69" NH="      1.09"/>
<constituent id="22" name="DryMatter" value="     21.60" GH="      1.69" NH="      1.09"/>
<constituent id="24" name="Glucose" value="      1.13" GH="      1.69" NH="      1.09"/>
<constituent id="25" name="Fructose" value="      1.42" GH="      1.69" NH="      1.09"/>
<constituent id="26" name="PIC" value="      8.68" GH="      0.00" NH="      0.00"/>
<constituent id="27" name="BIC" value="     12.28" GH="      0.00" NH="      0.00"/>
<constituent id="31" name="TRS" value="     11.69" GH="      0.00" NH="509313097534660010000000000000000.00"/>
<constituent id="32" name="Purity" value="     72.31" GH="      0.00" NH="      0.00"/>
</sample>
</result>

[Meetee]

Where's the question?. Explain your code and problem.