public ActionResult Working(Nullable <int> id)
        {
            if (id == null)
            {
                return(RedirectToAction("Index"));
            }
            if (TempData["status"] != null)
            {
                ViewBag.status = TempData["status"];
                ViewBag.msg    = TempData["msg"];
            }
            UserViewModel user = Session["User"] as UserViewModel;

            if (user.assistance != null)
            {
                IActivityDAL dalAct = new ActivityImpl();
                ActivitieAssistanceViewModel aa2 = ActivitieAssistanceViewModel.Converter(dalAct.GetCurrentActivity(user.assistance.idAssistance));
                ActivitieAssistanceViewModel aa  = ActivitieAssistanceViewModel.Converter(dalAct.GetActivity_Assistance(id.GetValueOrDefault()));
                if (aa2 == null || aa2.idActivityAssistance != id)
                {
                    return(RedirectToAction("Index"));
                }
                ActivityViewModel activity;
                using (var u = new UnitWork <Activity>()) {
                    activity = ActivityViewModel.Converter(u.genericDAL.Get(aa.idActivity));
                }
                if (activity == null)
                {
                    ViewBag.status = false;
                    ViewBag.msg    = "Error al encontrar la actividad actual";
                }
                else
                {
                    ViewBag.status = true;
                    ViewBag.msg    = "Actividad en curso";
                }
                aa.activity = activity;
                return(View(aa));
            }
            else
            {
                TempData["status"] = false;
                TempData["msg"]    = "Error al obtener la actividad";
            }
            return(RedirectToAction("Index"));
        }