[Solved] Menu disappears

[Samuel]

Hi. I'm using your menu for ASP.NET MVC bound to an XmlSitemap just as you show in the example of SiteMap Data Binding under Menu. The problem I'm having is that after some time using the application the menu disappears. It comes back again when I log in with another user or with the same one. My first thought was that I had to register the sitemap once again due to a session timeout or something of that sort, but when I execute the registration code 

if (HttpContext.uGetUserTypeId().ToInt() == 1)
                {
                    if (!SiteMapManager.SiteMaps.ContainsKey("E_PLAN_RD_ADMINISTRADOR"))
                    {
                        SiteMapManager.SiteMaps.Register<XmlSiteMap>("E_PLAN_RD_ADMINISTRADOR", sitmap => sitmap.LoadFrom("~/Content/SiteMaps/E_PLAN_RD_ADMINISTRADOR.sitemap"));

                    }
                }

the inner condition is never true. 
What could be causing this odd behavior?