Sync volume between 2 devices

Hi,

I’m trying to create an automation for my Denon receiver and Denon soundbar. When i change the volume of the receiver i want to change to volume of my soundbar accordingly. So i change the volume of the receiver by 2 up or down the soundbar must change it’s volume by 1 or something like that. The automation that i made keeps throwing an error when i want to save but i don’t know how to solve it.
The error: Message malformed: expected float for dictionary value @ data['action'][0]['choose'][0]['conditions'][2]['below']

My automation:

		  
alias: Sync Volume - Device 1 to Device 2
trigger:
  platform: state
  entity_id: media_player.device_1
condition:
  condition: and
  conditions:
    - condition: state
      entity_id: media_player.device_1			  
      state: 'digicorder'
    - condition: state
      entity_id: media_player.device_2
      state: 'coaxial'
action:
  - choose:
      - conditions:
          - condition: template
            value_template: "{{ trigger.from_state.attributes.volume_level is defined }}"
          - condition: template
            value_template: "{{ trigger.to_state.attributes.volume_level is defined }}"
          - condition: numeric_state
            entity_id: media_player.device_1
            below: "{{ (trigger.to_state.attributes.volume_level | float) - 2 }}"
            above: "{{ (trigger.to_state.attributes.volume_level | float) + 2 }}"
        sequence:
          - service: media_player.volume_down
            data:
              entity_id: media_player.device_2
          - delay: '00:00:01'
          - service: media_player.volume_down
            data:
              entity_id: media_player.device_2
      - conditions:
          - condition: template
            value_template: "{{ trigger.from_state.attributes.volume_level is defined }}"
          - condition: template
            value_template: "{{ trigger.to_state.attributes.volume_level is defined }}"
          - condition: numeric_state
            entity_id: media_player.device_1
            above: "{{ (trigger.to_state.attributes.volume_level | float) + 2 }}"
            below: "{{ (trigger.to_state.attributes.volume_level | float) - 2 }}"
        sequence:
          - service: media_player.volume_up
            data:
              entity_id: media_player.device_2
          - delay: '00:00:01'
          - service: media_player.volume_up
            data:
              entity_id: media_player.device_2