从ASP上传文档.Net到Sharepoint服务器

我正在尝试从ASP上传文件。Net到Sharepoint(为了保留时间戳，我使用这种方式)

    protected void UploadFileToSharePoint(string UploadedFilePath, string SharePointPath)
    {
        WebResponse response = null;
        try
        {
            string SUrl = "http://MysharepointPath/Folder";
            //WebRequest request = WebRequest.Create(SharePointPath);
            WebRequest request = WebRequest.Create(SUrl);
            request.Credentials = new NetworkCredential(username,password );
            //request.Method = "PUT";
            request.Method = "POST";
            FileStream fStream = File.OpenRead(UploadedFilePath);
            string fileName = fStream.Name.Substring(3);
            byte[] contents = new byte[fStream.Length];
            fStream.Read(contents, 0, (int)fStream.Length);
            fStream.Close();
            request.ContentLength = 0;
            //Custom code
            using (WebClient uploader = new WebClient())
            {
                try
                {
                    uploader.UploadFile(new Uri(SUrl), UploadedFilePath);
                }
                catch (Exception ex)
                {
                }
            }
            response = request.GetResponse();
        }
 }

当我尝试在调试模式下运行代码时，它抛出异常

"远程服务器返回错误401 unauthorized"