ASP.Net MVC: Redirect to login page when session timed out using ActionFilter not working

Hi,

how to redirect to login page is session is out?

below code is working fine when i clear cache in browser and refresh the page means it will redirecting to login, but when session is out after that when i click some button with ajax call it will not redirecting to login when session is out

below code i used

[AutorizeUser] 
public class HomeController : Controller {

}

public class AutorizeUser : ActionFilterAttribute, IActionFilter
{
    /// <summary>
    /// 
    /// </summary>
    /// <param name="filterContext"></param>
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        if (HttpContext.Current.Session["UserIsLoginIn"] == null)
        {
            filterContext.Result = new RedirectToRouteResult(new RouteValueDictionary {
                {"Controller", "Login" },
                {"Action", "Index" }
            });
        }
        base.OnActionExecuting(filterContext);
    }
}