c# – 为什么我会得到Soap异常？

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ConsoleApplication3.TestReference;
using System.IO;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            string srcUrl = @"C:......comp_name.xlsx";
            FileStream fStream = File.OpenRead(srcUrl);
            string fileName = fStream.Name.Substring(3);
            byte[] contents = new byte[fStream.Length];
            fStream.Read(contents,(int)fStream.Length);
            fStream.Close();

            ServiceWebReference.Lists listService = new ServiceWebReference.Lists();
            listService.Credentials = System.Net.CredentialCache.DefaultCredentials;

            try
            {
                // adding attachment
                string result = listService.AddAttachment("testList","1",fileName,contents);
                Console.WriteLine(result);
            }
            catch (System.Web.Services.Protocols.SoapException e)
            {
                Console.WriteLine(e.GetBaseException());
                Console.WriteLine(e);
            }
        }
    }
}

我得到Unhandled SOAP异常….
以下是我得到的完整例外情况：

System.Web.Services.Protocols.SoapException: Exception of type 'Microsoft.SharePoint.SoapServer.SoapServerException' was thrown.
  at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message,WebResponse response,Stream responseStream,Boolean asyncCall)
  at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName,Object[] parameters)
  at ConsoleApplication3.ServiceWebReference.Lists.AddAttachment(String listName,String listItemID,String fileName,Byte[] attachment) 
    in z:XxxxlTestCConsoleApplication3ConsoleApplication3Web ReferencesServiceWebReferenceReference.cs:line 782
  at ConsoleApplication3.Program.Main(String[] args) 
    in z:XxxxlTestCConsoleApplication3ConsoleApplication3Program.cs:line 29

Press any key to continue . . .

我正确地添加了引用：http ….. /_vti_bin/lists.asmx

我该怎么调试呢？在我的情况下,SOAP异常是什么？