if (sendtime > DateTime.Now)
                    {
                        if (timer == null)
                        timer = new System.Timers.Timer();
                        timer.Interval = sendtime.Subtract(DateTime.Now).TotalMilliseconds;
                        timer.Enabled = true;
                        timer.AutoReset = false;
                        timer.Elapsed += new ElapsedEventHandler(timer_Elapsed);
                    }