Scheduling on DateTime with process

Dear Guys,
   i need simple clarifications about scheduling datetime fucntions. and i create an solution with Scheduled based notification, and its based upon appropirate time with date.
  Its not properly checking the scheduled date, and its start process immediately.
  Can you please check that below code, im doing any thing wrong on it.!!
FOR Ex: sch_date = "09/10/2013 19:25:55";
another will come as like i mentieod with tempd string.!
DateTime sch_date = Convert.ToDateTime(dr["schedule_date"]);                         string dt = sch_date.ToString("MM/dd/yyyy HH:mm:ss");                         string tempd = DateTime.Now.ToShortDateString()  ...