Having trouble with automation and "below"

Hi,
Trying to run an automation when my powerplug goes below 15Watt.
I was following this doc: https://www.home-assistant.io/docs/automation/trigger/ with th example of above and below values, but when trying to use them I get an error: “Message malformed: extra keys not allowed @ data[‘below’]”

Originally I thought I could use “to: <20” but that doesn’t work. When I set it to “to: 0”, the automation works as I want. But the value isn’t always 0, sometimes 2W, so I need to find a way to detect below 15Watt.

This is the working code for value to 0 Watt, and wherever I try to add “below: 15” instead of to, I get the message malformed error:

- id: '1606240905567'
  alias: AUT002 Koffie is klaar
  description: Notificatie als de koffie klaar is
  trigger:
  - platform: state
    entity_id: sensor.powerplug001_energy_power
    for: 00:00:20
    to: '0'
  condition: []
  action:
  - service: notify.telegram
    data:
      message: De koffie is klaar
  mode: single

You are using a state trigger. You need to use a numeric state trigger. See: https://www.home-assistant.io/docs/automation/trigger/#numeric-state-trigger

State triggers are for on/off

Numeric state triggers are for number comparisons.

Ah… that did the trick. Thank you