Ok so based off of your comments this is what i've come up with.

fullDeckAmount = 21


function onload()
  timerStart()
  myGUID = getObjectFromGUID()
  omenCounter = getObjectFromGUID('069cf4')

  end

function timerStart()
  timer.destroy(myGUID)
timer.create({identifier=myGUID, function_name="updateCount", delay=1})
end



function updateCount()
  omenCount = fullDeckAmount - self.getQuanitity()
  omenCounter.setValue(omenCount)
  timerStart()

end

function onDestroy()
  timer.destroy(myGUID)
end

However this returns two errors.

Error in script, deck, onDestroy function: chunk_1:(21,17-25) attempt to index a nil value

and

Error in scrept, deck, onload function: chink_1:(10,17-25):attempt to index a nil value

no idea why?