Problem with Asp.net MVC routes

I have an application that I put in as a new site and it worked perfectly, but by putting that application inside another, it gives an error in the route. I need to sign in when you sign in to " link " and it is pointing to " link ". Excerpt where it returns to the "PainelAdm" view:

[HttpPost]
        public ActionResult LogOn(FormCollection f, string returnUrl)
        {
            Conta user = new Conta();
            ContaModels atrrConta = new ContaModels();
            atrrConta = user.RetornaUser(f["login"]); 
            if (user.AutenticaUser(atrrConta, f["senha"]))
            {
                //Rotina para autenticar usuario
                if (returnUrl == "" || returnUrl == null)
                {
                    returnUrl = "/CalendarioAlertaSMS";
                }

                System.Web.Security.FormsAuthentication.SetAuthCookie(atrrConta.Ide_Perfil.ToString(), false); 

                Session["PERFIL"] = atrrConta.Ide_Perfil;
                Session["NOME"] = atrrConta.Nome;

                if (Session["PERFIL"].ToString() == "ADMIN")
                {
                     returnUrl = "/PainelAdm"; 
                }

                return Redirect(returnUrl);
            }
            else
            {
                ViewBag.Message = "Login ou senha inválidos.";
                return View();
            }
        }