Help with shelly dimmer 2

Hi, please can someone advise why I am not able to use the dimming functionality in lovelace with this yaml? The light switches on and off fine but won’t dim.

mqtt:
  light:
    - name:  "Office_inner"   
      schema: template
      state_topic: "shellies/shellydimmer2-[deviceID]/light/0/status"
      state_template: "{% if value_json.ison %} on {% else %} off {% endif %}"
      command_topic: "shellies/shellydimmer2-[deviceID]/light/0/set"
      command_on_template: >
         {"turn": "on"
         {%- if brightness is defined -%}
         , "brightness": {{brightness | float | multiply(0.3882) + 1 | round(0)}}
         {%- endif -%}}
      command_off_template: '{"turn": "off"}'
      brightness_template: "{{ value_json.brightness | float | multiply(2.55) | round(0) }}"