Creating an xml document with the xsi:schemalocation attribute.
Everytime i create the file it takes the xsi prefix off! Anyideas why it would do this?

See Code below


Code:
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim xmldoc As New System.Xml.XmlDocument
        Dim xmlproc As System.Xml.XmlDeclaration
        Dim xmlroot As System.Xml.XmlElement
        Dim xmlchild As System.Xml.XmlElement
        Dim xmlAttri As System.Xml.XmlAttribute
        Dim xmlOutputfile As New System.Xml.XmlTextWriter("c:\Simplexml.xml", System.Text.Encoding.UTF8)

        xmlproc = xmldoc.CreateXmlDeclaration("1.0", "", "")
        xmldoc.AppendChild(xmlproc)

        xmlroot = xmldoc.CreateElement("invoice")

        xmlAttri = xmldoc.CreateAttribute("xmlns")
        xmlAttri.Value = "http://www.test.info"
        xmlroot.Attributes.Append(xmlAttri)

        xmlAttri = xmldoc.CreateAttribute("xmlns:xsi")
        xmlAttri.Value = "http://www.w3.org/2001/XMLSchema-instance"
        xmlroot.Attributes.Append(xmlAttri)


        xmlAttri = xmldoc.CreateAttribute("schemaLocation")
        xmlAttri.Value = "http://NamespaceTest.com/Purchase test_xml_feed.xsd"
        xmlroot.Attributes.Append(xmlAttri)



        xmlchild = xmldoc.CreateElement("provider_ref")
        xmlchild.InnerText = "1234"
        xmlroot.AppendChild(xmlchild)

        xmlchild = xmldoc.CreateElement("supplier_name")
        xmlchild.InnerText = "A Supplier"
        xmlroot.AppendChild(xmlchild)

        xmlchild = xmldoc.CreateElement("period")
        xmlchild.InnerText = "2008-05-04"
        xmlroot.AppendChild(xmlchild)

        xmlchild = xmldoc.CreateElement("invoice_number")
        xmlchild.InnerText = "000000001"
        xmlroot.AppendChild(xmlchild)

        xmlroot.AppendChild(xmlchild)

        xmldoc.AppendChild(xmlroot)

        xmldoc.WriteTo(xmlOutputfile)
        xmlOutputfile.Close()

    End Sub