C# - Добавление вложения к элементу списка Sharepoint 2010 - Attach file to list item

//CreateWithAttachment(ServiceURL,ListName,"158","");
        const string ListName = "NAME OF YOUR LIST";
        const string ServiceURL = "http://mysite/sites/sitename/_vti_bin/Lists.asmx";
        class CreateState
        {
            public bool hasErrors;
            public string returnMessage;
            public string fileName;
        }
 
        //webservicename- name of your web service
        CreateState CreateWithAttachment(string serviceurl, string listname, string itemid, string filename)
        {
            CreateState cs = new CreateState();
            cs.fileName = Path.GetFileName(filename);
            if (File.Exists(filename))
            {
                byte[] contents = System.IO.File.ReadAllBytes(filename);
                webservicename.Lists listService = new webservicename.Lists();
                listService.Credentials = System.Net.CredentialCache.DefaultCredentials;
                listService.Url = serviceurl;
                try
                {
                    string addAttach = listService.AddAttachment(listname, itemid,
                    cs.fileName, contents);
                    cs.hasErrors = false;
                    cs.returnMessage = addAttach;
                    return cs;
                }
                catch (System.Web.Services.Protocols.SoapException ex)
                {
                    cs.hasErrors = true;
                    cs.returnMessage = "ERROR: \n"  +
                        ex.Detail.InnerText ;
                    return cs;
                }
            }
            else
            {
                cs.hasErrors = true;
                cs.returnMessage = "ERROR: file not found";
                return cs;
            }
        }