c# timer定时器的关闭问题

1.开启

public static Timer aTimer;
        public void SignalrLine()
        {
            SetTimerParam();
        }
        private void test(object source,System.Timers.ElapsedEventArgs e)
        {
            //访问后台数据库，获取数据，传递到前台，进行报警。
            var mb = (from r in db.BSB_Warm_Records where r.tab != true orderby r.id select r).FirstOrDefault();
            var mb1 = mb.StationName;
            Clients.All.sendMessage(mb1);
        }
        public void SetTimerParam()
        {
            aTimer = new Timer();
            aTimer.Elapsed += new ElapsedEventHandler(test);
            aTimer.Interval = 5000;
            aTimer.AutoReset = true;
            aTimer.Enabled = true;
        }

2.关闭

public void StopTimer()
        {
            aTimer.Stop();
            //aTimer.Enabled = false;
        }