我自定义了一个ExceptionFilter  用于DoRelease这个Action，但结果是异常老是未捕获跳不到错误页面，请问是什么问题呢？本人是刚刚接触ASP.NET MVC模式

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Ajax;

namespace MVCDemo.Controllers.Filters
{
    public class ExceptionFilter : FilterAttribute,IExceptionFilter
    {
        void IExceptionFilter.OnException(ExceptionContext filterContext)
        {
            filterContext.Controller.ViewData["ErrorMessage"] = filterContext.Exception.Message;
            filterContext.Result = new ViewResult()
            {
                ViewName = "Error",
                ViewData = filterContext.Controller.ViewData,
            };
            filterContext.ExceptionHandled = true;
        }
    }
}

      [ExceptionFilter()]
        public ActionResult DoRelease()
        {
            AnnounceInfo announce = new AnnounceInfo()
            {
                ID = 1,
                Title = Request.Form["Title"],
                Category = Int32.Parse(Request.Form["Category"]),
                Content = Request.Form["Content"],
            };

            IAnnounceService aServ = ServiceBuilder.BuildAnnounceService();

                aServ.Release(announce);      //该条语句发生异常
   

            ViewData["Announce"] = announce;

            System.Threading.Thread.Sleep(2000);
            ViewData["Time"] = DateTime.Now;
            System.Threading.Thread.Sleep(2000);

            return View("ReleaseSucceed");
        }