Issue Coming When I Am Adding My Site Url To Google Webmaster Tool

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C#5.0

i am using this code and every time i am getting error in c#

GDataRequestException, Execution of authentication request returned unexpected result: 404

For adding site

Google.GData.Client.RequestSettings settings = new Google.GData.Client.RequestSettings("ProjektName", "E-MAIL", "PWD");
Google.WebmasterTools.WebmasterToolsRequest f = new Google.WebmasterTools.WebmasterToolsRequest(settings);

Google.WebmasterTools.Sites site = new Google.WebmasterTools.Sites();
site.AtomEntry = new Google.GData.Client.AtomEntry();
site.AtomEntry.Content.Src = "http://www.example.com/";
site.AtomEntry.Content.Type = "text/plain";
Google.WebmasterTools.Sites newSite = f.AddSite(site);



For adding sitemap

Google.WebmasterTools.Sitemap sitemap = new Google.WebmasterTools.Sitemap();
sitemap.Id = "http://www.example.com/sitemap.xml";
sitemap.Categories.Add(new Google.GData.Client.AtomCategory("http://schemas.google.com/webmasters/tools/2007#site-info", new Google.GData.Client.AtomUri("http://schemas.google.com/g/2005#kind")));
sitemap.SitemapType = "WEB";
Google.WebmasterTools.Sitemap newSitemap = f.AddSitemap("http%3A%2F%2Fwww%2Eexample%2Ecom%2F", sitemap);


can anybody please help me