Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
        strXML = TextBox1.Text
        Dim mstream As New IO.MemoryStream()
        Dim stw As New IO.StreamWriter(mstream)
        Try
            stw.Write(strXML)
            stw.Flush()
 
            strvalidationErgebnis = ""
            Dim settings As XmlReaderSettings = New XmlReaderSettings
            settings.ValidationType = ValidationType.Schema
            settings.ValidationFlags = settings.ValidationFlags Or _
              XmlSchemaValidationFlags.ProcessSchemaLocation
            settings.ValidationFlags = settings.ValidationFlags Or _
            XmlSchemaValidationFlags.ReportValidationWarnings
            AddHandler settings.ValidationEventHandler, AddressOf _
            ValidationCallBack
 
            ' Create the XmlReader object.
            Dim reader As XmlReader = XmlReader.Create(mstream, settings)
            ' Parse the file. 
            While (reader.Read())
            End While
            MsgBox(strvalidationErgebnis)
            reader.Close()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try
 
    End Sub
    ' Display any warnings or errors.
    Private Sub ValidationCallBack(ByVal sender As Object, ByVal args As _
      ValidationEventArgs)
        If (args.Severity = XmlSeverityType.Warning) Then
            strValidationErgebnis += vbCrLf & "   Warning: Matching schema not" & _
              "found.  No validation occurred." + args.Message
        Else
            strValidationErgebnis += vbCrLf & "   Validation error: " + _
              args.Message
        End If
    End Sub