title: WebClient DownloadFileAsync() does not work
body: <p>WebClient DownloadFileAsync() does not work with the same URl and Credentials... </p>
  
  <p>Any clue?</p>
  
  <pre><code> static void Main(string[] args)
          {
              try
              {
                  var urlAddress = "http://mywebsite.com/msexceldoc.xlsx";
  
  
                  using (var client = new WebClient())
                  {
                      client.Credentials = new NetworkCredential("UserName", "Password");
                      // It works fine.  
                      client.DownloadFile(urlAddress, @"D:\1.xlsx");
                  }
  
                  /*using (var client = new WebClient())
                  {
                     client.Credentials = new NetworkCredential("UserName", "Password");
  
                      // It y creats file with 0 bytes. Dunow why is it. 
                      client.DownloadFileAsync(new Uri(urlAddress), @"D:\1.xlsx");
                      //client.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);
  
                  }*/
              }
              catch (Exception ex)
              {
  
              }
          }
  </code></pre>