DispatcherTimer没有在task内工作

效果如下

public MainWindow()
{
    CheckCrawlURLs.func_StartCrawlingWaitingUrls();    
}

但是在

下面不起作用

public MainWindow()
{                 
    Task.Factory.StartNew(() =>
    {
        CheckCrawlURLs.func_StartCrawlingWaitingUrls();
    });
}

下面是两个例子中执行的类

public static class CheckCrawlURLs
{
    public static void func_StartCrawlingWaitingUrls()
    {
        PublicStaticFunctions.AddMsgToEvents("Checking waiting crawling urls process started");
        System.Windows.Threading.DispatcherTimer dispatcherTimer = new System.Windows.Threading.DispatcherTimer();
        dispatcherTimer.Tick += new EventHandler(func_CheckWaitingUrls);
        dispatcherTimer.Interval = new TimeSpan(0, 0, 5);
        dispatcherTimer.Start();
    }
    private static void func_CheckWaitingUrls(object sender, EventArgs e)
    {
        PublicStaticFunctions.AddMsgToMoreCommonEvents("Checking waiting to crawl urls...");
        List<string> lstStartCrawling = CrawlURLDB.func_ReturnNextCrawlLinks();
        PublicStaticFunctions.AddMsgToMoreCommonEvents("Number of links to start crawlin: " + lstStartCrawling.Count);
    }
}

我的问题是这里的逻辑是什么?

在第二个任务工厂启动时，func_CheckWaitingUrls没有滴答。