Why the "RunWorkerCompleted" never comes after pressing ENTER?

[senglory]

using System;
using System.ComponentModel ;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Reflection;


namespace Retriever
{
    class Program
    {
        static void Main(string[] args)
        {
            BackgroundWorker bw = new BackgroundWorker();
            bw.WorkerSupportsCancellation = true;
            

            bw.DoWork += new DoWorkEventHandler(bw_DoWork);
            bw.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bw_RunWorkerCompleted);
            bw.RunWorkerAsync();
            Console.WriteLine("Press ENTER to exit...");
            Console.ReadLine();
            bw.CancelAsync();
            Thread.Sleep(5000);
        }

        static void bw_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Cancelled )
                cls.Suspend ();
        }

        static void bw_DoWork(object sender, DoWorkEventArgs e)
        {
 for (int i = 0; i < 10000; i++){ Thread.Sleep(1000); Console.WriteLine(i); if (e.Cancel){e.Result = "done"; return ;}}        }
    }
}

If to hit Enter after running, the bw_RunWorkerCompleted() will be never invoked. Why?