obtener el número de línea achivo xml

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim xdoc As XDocument = XDocument.Load("archivo.xml", LoadOptions.SetLineInfo)
        Dim categories As IEnumerable(Of XElement) = xdoc.Descendants("TipoDespacho")
        For Each category As XElement In categories
            Dim lineNumber As Integer = CType(category, IXmlLineInfo).LinePosition
        Next
    End Sub