Is this correct

I’m trying to display a timer, bit its not working is this correct?

startTimer = function()
  if start_timer > 0 then
    start_timer -= 1/60
    else
      start_timer = 0
      starttimer = true
  end
end
TimerDraw = function()
  screen.drawText(":" + ceil(start_timer) ,0,25,"rgba(35,225,225)")
  end

the only thing i can notice that is wrong is that starttimer is wrong and should be the same as the other ones.

assuming you're calling startTimer() every update, then I don't see an issue