The remote server returned an error: (401) Unauthorized

{
            String url = url;


            try
            {

                HttpWebRequest webRequest = WebRequest.Create(url) as HttpWebRequest;
                webRequest.PreAuthenticate = true;
                webRequest.UseDefaultCredentials = false;
                webRequest.Credentials = new NetworkCredential("account", "password", "domain");
                WebResponse response = webRequest.GetResponse();
                using (StreamReader reader = new StreamReader(response.GetResponseStream()))
                {
                    HtmlAgilityPack.HtmlDocument doc = new HtmlAgilityPack.HtmlDocument();
                    doc.Load(reader);



                    TTGL = doc.DocumentNode.SelectSingleNode("//xpath[2]").InnerText.Trim();

                    //*[@id='wu-publication']/div[2]/div/div[2]/p[2]/text()

                    //Prerequisites list<String> items
                    List<String> temList = new List<string>();
                    var res = doc.DocumentNode.SelectSingleNode("//*[@id='wu-prerequisites-list']/ul");
                    if (res != null)
                    {
                        var list = res.SelectNodes(@"li");

                        if (list.Count > 0)
                        {
                            foreach (var item in list)
                            {
                                temList.Add(item.InnerText.Trim().ToString());
                            }
                        }
                    }

                    //private List<SupersedenceUpdate> supersededUpdates;
                    List<SupersedenceUpdate> tmpSSList = new List<SupersedenceUpdate>();
                    res = doc.DocumentNode.SelectSingleNode("//*[@id='wu-supersedence']/table/tbody");
                    if (res != null)
                    {
                        var trList = res.SelectNodes(@"tr");
                        if (trList != null)
                        {
                            foreach (var i in trList)
                            {
                                SupersedenceUpdate ss = new SupersedenceUpdate();
                                var tdList = i.SelectNodes(@"td");
                                if (tdList.Count > 0)
                                {
                                    ss.Title = tdList[0].InnerText.Trim();
                                    ss.UpdateId = tdList[1].InnerText.Trim();
                                    ss.Rev = tdList[2].InnerText.Trim();
                                    ss.TTGL = tdList[3].InnerText.Trim();
                                    ss.State = tdList[4].InnerText.Trim();
                                }
                                tmpSSList.Add(ss);
                            }
                        }
                    }


                    //private List<SupersedenceUpdate> supersedingUpdates;            
                    tmpSSList = new List<SupersedenceUpdate>();
                    res = doc.DocumentNode.SelectSingleNode("//*[@id='wu-superseding']/table/tbody");
                    if (res != null)
                    {
                        var trList = res.SelectNodes(@"tr");
                        if (trList != null)
                        {
                            foreach (var i in trList)
                            {
                                SupersedenceUpdate ss = new SupersedenceUpdate();
                                var tdList = i.SelectNodes(@"td");
                                if (tdList.Count > 0)
                                {
                                    ss.Title = tdList[0].InnerText.Trim();
                                    ss.UpdateId = tdList[1].InnerText.Trim();
                                    ss.Rev = tdList[2].InnerText.Trim();
                                    ss.TTGL = tdList[3].InnerText.Trim();
                                    ss.State = tdList[4].InnerText.Trim();
                                }
                                tmpSSList.Add(ss);
                            }
                        }
                    }

                    //MessageBox.Show("Got it!");
                }

            }
            catch (WebException ex)
            {
                MessageBox.Show(ex.ToString());
            }
        }