vb.net - Run function each day at set time -

so have app need run email function each day @ time set. in case set 6pm. left running , went home work. @ 6pm received email function ran. come midnight ran again, , because ran @ midnight , that's technically today, won't run again until 6pm next day instead of 6pm tonight since ran @ midnight. can't figure out what's wrong , why ran @ midnight.

private target datetime private state maintenancestate = maintenancestate.waitingtostart public maintenancetime new timespan(hour, min, 0) private waitinginterval new timespan(0, 5, 0) ' 5 minutes  private enum maintenancestate     waitingtostart     started end enum  private sub tmr_maintenance_tick(sender object, e eventargs) handles tmr_maintenance.tick     dim ts timespan = target.subtract(datetime.now)     lblstatus.text = ts.tostring("hh\:mm\:ss")     if datetime.now >= target         tmr_maintenance.stop()         select case state             case maintenancestate.waitingtostart                 sendemail()                 state = maintenancestate.started                 target = datetime.now.add(waitinginterval)             case maintenancestate.started                 if done = 1                     target = datetime.now.add(waitinginterval)                 else                     state = maintenancestate.waitingtostart                     target = getnextmaintenancetarget(maintenancetime)                 end if         end select         tmr_maintenance.start()     end if end sub  private function getnextmaintenancetarget(byval time timespan) datetime     dim dt datetime = datetime.today.add(time)     if datetime.now > dt         dt = dt.adddays(1)     end if     return dt end function 

i suggest removing code scheduling , instead schedule executable run using task scheduler.