TimePicker和dispatcherTimer windows phone 8

Question

    private async Task tick()
    {
        DateTime start = DateTime.Now;
        DateTime end = (DateTime)time1.Value;
        string expirationTime = (start.ToShortTimeString()) + (end.ToShortTimeString());
        ts1 = end.Subtract(start);
        messageTime = new DispatcherTimer();
        messageTime.Interval = TimeSpan.FromSeconds(ts1.TotalSeconds);
        messageTime.Tick += messageTime_Tick;
    }

    private void messageTime_Tick(object sender, object e)
    {
        if (ts1.TotalSeconds < 2)
        {
            MessageBox.Show("Done");
            message();
        }
    }

出于某种原因，我没有收到消息框说完了。我在这里做错了吗？提前谢谢！

Answer 1

TimeSpan.FromSeconds(1);
messageTime.Start();