Error passing URL as parameter ... JoeBlogs & HtmlAgilityPack

Main

namespace ReaderXML
{
    class Program
    {
        static void Main(string[] args)
        {
            var website = LeitorDeXML("http://SITE ORIGEM/").ToArray();
            var total = website.Count();
            for (int i = 1; i < total; i++)
            {
                Postagem(website[i]);
            }
        }

Method for blog post

    private static void Postagem(string website)
        {
            try
            {
                //LINK,USER,SENHA WP
                string link = "http://SITE NOVO";
                string username = "user wp";
                string password = "senha wp";

                //Leitura do HTML
                HtmlWeb web = new HtmlWeb();
                HtmlDocument resultat = web.Load(website);

                //Separar TITULO e CONTEUDO
                string titulopost = resultat.DocumentNode.SelectNodes("//*[contains(@class,'entry-title')]")[0].InnerHtml;
                string conteudo = resultat.DocumentNode.SelectNodes("//*[contains(@class,'entry-content')]")[0].InnerHtml; //ERRO AQUI

                //Entrada no wp
                var wp = new WordPressWrapper(link + "/xmlrpc.php", username, password);
                var post = new Post();

                //Categoria -- Não está funcionando ainda a parte da criação da categoria

                int website_corpo = 25;
                string categoria = website.Substring(website_corpo);
                int indexof_barra = categoria.IndexOf("/");
                int comeco_cat = 0;
                string categoria_f = categoria.Substring(comeco_cat, indexof_barra);

                //Data

                post.DateCreated = DateTime.Today.AddHours(0);

                //Postagem
                post.Title = titulopost;
                post.Body = conteudo;

                wp.NewPost(post, true);
            }
            catch (Exception e)
            {
                Console.WriteLine("Error: {0}", e);
                Console.ReadKey();
            }
        }
    }
}

The "ReadModel" method reads a declared sitemap in MAIN and returns me the latest urls.

The problem is that when I pass this url as a parameter, at the time it takes the "content string" it goes no further.

Give the following error:

  

Error: System.NullReferenceException: Object reference not set to   an instance of an object