System.NullReferenceException

[Vinicius]

ASP.NET MVC 2

I'm getting the following error:

[NullReferenceException: Referência de objeto não definida para uma instância de um objeto.]
   Telerik.Web.Mvc.Infrastructure.Implementation.AuthorizeAttributeCache.GetAuthorizeAttributes(RequestContext requestContext, String controllerName, String actionName) +230
   Telerik.Web.Mvc.Infrastructure.Implementation.ControllerAuthorization.IsAccessibleToUser(RequestContext requestContext, String controllerName, String actionName) +171
   Telerik.Web.Mvc.Infrastructure.Implementation.NavigationItemAuthorization.IsAccessibleToUser(RequestContext requestContext, INavigatable navigationItem) +269
   Telerik.Web.Mvc.UI.<>c__DisplayClass2`1.<IsAccessible>b__1(T item) +76
   System.Linq.Enumerable.Any(IEnumerable`1 source, Func`2 predicate) +159
   Telerik.Web.Mvc.UI.NavigatableExtensions.IsAccessible(IEnumerable`1 items, INavigationItemAuthorization authorization, ViewContext viewContext) +321
   Telerik.Web.Mvc.UI.Menu.WriteItem(MenuItem item, IHtmlNode parentTag, IMenuHtmlBuilder builder) +443
   Telerik.Web.Mvc.UI.<>c__DisplayClass4.<WriteHtml>b__3(MenuItem item) +58
   Telerik.Web.Mvc.Extensions.EnumerableExtensions.Each(IEnumerable`1 instance, Action`1 action) +230
   Telerik.Web.Mvc.UI.Menu.WriteHtml(HtmlTextWriter writer) +430
   Telerik.Web.Mvc.UI.ViewComponentBase.Render() +147
   Telerik.Web.Mvc.UI.ViewComponentBuilderBase`2.Render() +55
   Telerik.Web.Mvc.UI.ViewComponentBuilderBase`2.ToString() +28
   Igreja.Web.MenuHelpers.CreateMenu(HtmlHelper html) in C:\Projetos\IgrejaOnline\Igreja\Igreja.Web\Helpers\MenuHelpers.cs:47
   ASP.views_shared_master_master.__Render__control1(HtmlTextWriter __w, Control parameterContainer) in c:\Projetos\IgrejaOnline\Igreja\Igreja.Web\Views\Shared\Master.master:48
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +256
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
   System.Web.UI.Control.Render(HtmlTextWriter writer) +10
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Control.RenderChildrenInternal(HtmlTextWriter writer, ICollection children) +134
   System.Web.UI.Control.RenderChildren(HtmlTextWriter writer) +19
   System.Web.UI.Page.Render(HtmlTextWriter writer) +29
   System.Web.Mvc.ViewPage.Render(HtmlTextWriter writer) +59
   System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter) +27
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer, ControlAdapter adapter) +99
   System.Web.UI.Control.RenderControl(HtmlTextWriter writer) +25
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1266


Here is my code:

using System;
using System.Web;
using System.Web.Mvc;
using Telerik.Web.Mvc.UI;
using Igreja.Data;
using System.Collections.Generic;
using System.Linq;

namespace Igreja.Web
{
    public static class MenuHelpers
    {
        public static string CreateMenu(this HtmlHelper html)
        {
            if (SessionHelper.Menu == null)
            {
                MenuBuilder menu = html.Telerik().Menu();
                menu = menu.Name("menu");

                var repository = RepositoryFactory<Pagina>.Get() as IRepositoryPagina;
                var paginas = repository.GetAll();

                IList<Pagina> raizes = repository.RaizesMenu();
                foreach (Pagina pagina in raizes)
                {
                    if (Seguranca.VerificarPermissao(SessionHelper.IdUsuario, pagina.Id))
                    {
                        if (string.IsNullOrEmpty(pagina.Action))
                        {
                            menu = menu.Items(item => item.Add()
                                                          .Text(pagina.Nome)
                                                          .AddMenuItems(SessionHelper.IdUsuario,
                                                                        pagina.Hierarquia));
                        }
                        else
                        {
                            menu = menu.Items(item => item.Add()
                                                          .Action(pagina.Action,
                                                                  pagina.Controller)
                                                          .Text(pagina.Nome)
                                                          .AddMenuItems(SessionHelper.IdUsuario,
                                                                        pagina.Hierarquia));
                        }
                    }
                }

                SessionHelper.Menu = menu.ToString();
            }

            return SessionHelper.Menu;
        }

        public static void AddMenuItems(this MenuItemBuilder itemBuilder, int idUsuario, string hierarquia)
        {
            var repository = RepositoryFactory<Pagina>.Get() as IRepositoryPagina;
            var paginas = repository.GetAll();

            IList<Pagina> subPaginas = repository.SubPaginas(hierarquia);
            foreach (Pagina pagina in subPaginas)
            {
                if (Seguranca.VerificarPermissao(idUsuario, pagina.Id))
                {
                    if (string.IsNullOrEmpty(pagina.Action))
                    {
                        itemBuilder = itemBuilder.Items(item => item.Add()
                                                                    .Text(pagina.Nome)
                                                                    .AddMenuItems(idUsuario,
                                                                                  pagina.Hierarquia));
                    }
                    else
                    {
                        itemBuilder = itemBuilder.Items(item => item.Add()
                                                                    .Action(pagina.Action,
                                                                            pagina.Controller)
                                                                    .Text(pagina.Nome)
                                                                    .AddMenuItems(idUsuario,
                                                                                  pagina.Hierarquia));
                    }
                }
            }
        }
    }
}