Alarm missing grp update

[Tokatubs]

Hi 

I am looking for a solution that i need an alarm if a group address is not updated within a certain time. 
Received a script from another user that was working in beginning. But when i tried to change the time down it dont seem to work anymore. 
Any thoughts? Original script below

Code:

heartbeat_time = 60 -- Minutes
heartbeat_device_object = '32/1/2' -- Change address to your heartbeat device
heartbeat_alarm_object = '32/1/3' -- Change address to a alarm address


hb_d_obj = grp.find(heartbeat_device_object)
hb_a_obj = grp.find(heartbeat_alarm_object)

if hb_d_obj then
  local delta = os.time() - hb_d_obj.updatetime
  if delta >= heartbeat_time * 60 and hb_a_obj.value == false then
    grp.write(heartbeat_alarm_object, true)
  elseif delta < heartbeat_time * 60 and hb_a_obj.value == true then
    grp.write(heartbeat_alarm_object, false)
  end
end