从具有名称空间的XML文件中读取数据

在下面的xml中，我需要获得以下值

rfc = " CODJ7002145Q3 UUID = " 07 beef18-45af-5f3b-bb44-c2758802adcf "

<?xml version="1.0" encoding="UTF-8"?>
    <cfdi:Comprobante xmlns:cfdi="http://www.sat.gob.mx/cfd/3" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sat.gob.mx/cfd/3 http://www.sat.gob.mx/sitio_internet/cfd/3/cfdv32.xsd" version="3.2" serie="C" folio="371" fecha="2015-03-04T12:48:04" sello="abnLKgvWQ+pPBW1YSI/N941kf7eDOn8GBttp1/AJAdkQS6n60s37saV9ugTfOpYM4G+Q+4zr0jn0RQldamFyMDo/F3BfPg3R9yG8SD5A45i4Sh3CL/El2AHH/Zkyvft8b+BgFAMCoauvpi61BOCNK1EjEPcro0eZoy8ZRBfv+Xo=" formaDePago="PAGO EN UNA SOLA EXHIBICION" noCertificado="00001000000301540335" certificado="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" subTotal="869.39" TipoCambio="1.00" Moneda="Peso Mexicano" total="828.82" tipoDeComprobante="ingreso" metodoDePago="NO IDENTIFICADO" LugarExpedicion="FRANCISCO I. MADERO 2017 , NUEVA, 21100, MEXICALI, MEXICALI, BAJA CALIFORNIA, MEXICO">
        <cfdi:Emisor rfc="CODJ7002145Q3" nombre="JORGE CORONA DURAN">
            <cfdi:DomicilioFiscal calle="FRANCISCO I. MADERO" noExterior="2017" colonia="NUEVA" localidad="MEXICALI" municipio="MEXICALI" estado="BAJA CALIFORNIA" pais="MEXICO" codigoPostal="21100"/>
            <cfdi:RegimenFiscal Regimen="PERSONA FISICA CON ACTIVIDAD EMPRESARIAL Y PROFESIONAL"/>
        </cfdi:Emisor>
        <cfdi:Receptor rfc="VME990127Q70" nombre="VSF MEXICO S.A. DE C.V., SOFOM, E.N.R.&#xA;">
            <cfdi:Domicilio calle="AVE SANTA FE&#xA;" noExterior="495" colonia="MANZANA B LOTE B1 20&#xA; COL. CRUZ MANCA&#xA;" localidad="MEXICO" municipio="CUAJIMALPA" estado="DISTRITO FEDERAL" pais="MEXICO" codigoPostal="05349"/>
        </cfdi:Receptor>
        <cfdi:Conceptos>
            <cfdi:Concepto cantidad="1.00" unidad="No aplica" noIdentificacion="RECU" descripcion="RECUPERACION" valorUnitario="869.39" importe="869.39"/>
        </cfdi:Conceptos>
        <cfdi:Impuestos totalImpuestosRetenidos="179.67" totalImpuestosTrasladados="139.10">
            <cfdi:Retenciones>
                <cfdi:Retencion impuesto="ISR" importe="86.94"/>
                <cfdi:Retencion impuesto="IVA" importe="92.73"/>
            </cfdi:Retenciones>
            <cfdi:Traslados>
                <cfdi:Traslado impuesto="IVA" tasa="16.00" importe="139.10"/>
            </cfdi:Traslados>
        </cfdi:Impuestos>
        <cfdi:Complemento>
            <tfd:TimbreFiscalDigital xmlns:tfd="http://www.sat.gob.mx/TimbreFiscalDigital" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.sat.gob.mx/TimbreFiscalDigital http://www.sat.gob.mx/TimbreFiscalDigital/TimbreFiscalDigital.xsd" selloCFD="abnLKgvWQ+pPBW1YSI/N941kf7eDOn8GBttp1/AJAdkQS6n60s37saV9ugTfOpYM4G+Q+4zr0jn0RQldamFyMDo/F3BfPg3R9yG8SD5A45i4Sh3CL/El2AHH/Zkyvft8b+BgFAMCoauvpi61BOCNK1EjEPcro0eZoy8ZRBfv+Xo=" FechaTimbrado="2015-03-04T14:48:50" UUID="07BEEF18-45AF-5F3B-BB44-C2758802ADCF" noCertificadoSAT="00001000000202864883" version="1.0" selloSAT="pnaIMS1fcN4BIkKmoibQQTYANHJeG+1uvwO32ZC4io0wM/INNnspsig9/R+GrCx+fHwCGmyISlU+WLgmww9G5IpB4YuNywJW1j0ggaFunW2hOyLfgmYC2IJeMPUCxrL8pd64NiyNMYzNb0zI/6miefmzgSnAAFZXAYB3YuAMoPo="/>
        </cfdi:Complemento>
    </cfdi:Comprobante>

下面是我正在使用的代码，但是我得到了一个异常:表达式必须计算为节点集。

Protected Function ProcessXml(ByVal fileName As String) As Boolean
            _import = True
            Try
                Dim xmlDoc As XmlDocument = New XmlDocument()
                Dim invNum As Integer = 0
                Dim vdetails As DataObjects.Voucher
                xmlDoc.Load(fileName)
                Library.Log("Start looping through the invoices " & fileName, LogType.INFOLOG, ImportType.ECOUNSEL_IMP)
                Dim nodeLst As XmlNodeList = xmlDoc.SelectNodes("/cfdi:Comprobante/")
                For Each vouch As XmlElement In nodeLst
                    Dim rfc As String = vouch("cfdi:Emisor/rfc").InnerText
                    Console.WriteLine(rfc)
                Next
            Catch ex As Exception
                Library.Log("eCounsel Imported errored out in processXml: " & ex.ToString(), LogType.ERRORLOG, ImportType.ECOUNSEL_IMP)
                _import = False
            End Try
            ProcessXml = _import
        End Function

Imports System.Xml
Imports System.Xml.Linq
Module Module1
    Const FILENAME As String = "c:'temp'test.xml"
    Sub Main()
        Dim doc As XDocument = XDocument.Load(FILENAME)
        Dim rfc As String = doc.Descendants().Where(Function(x) x.Name.LocalName = "Receptor").Select(Function(x) CType(x.Attribute("rfc"), String)).FirstOrDefault()
        Dim UUID As String = doc.Descendants().Where(Function(x) x.Name.LocalName = "TimbreFiscalDigital").Select(Function(x) CType(x.Attribute("UUID"), String)).FirstOrDefault()
    End Sub
End Module

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Xml.Linq;
namespace ConsoleApplication2
{
    class Program
    {
        const string FILENAME = @"c:'temp'test.xml";
        static void Main(string[] args)
        {
           XDocument doc = XDocument.Load(FILENAME);
           string rfc = doc.Descendants().Where(x => x.Name.LocalName == "Receptor").Select(x => (string)x.Attribute("rfc")).FirstOrDefault();
           string UUID = doc.Descendants().Where(x => x.Name.LocalName == "TimbreFiscalDigital").Select(x => (string)x.Attribute("UUID")).FirstOrDefault();
        }
    }
}