Problem passing brightness value

Hello,

I have trouble passing brightness value to a custom built dimmer.

Here is my yaml definition:

- unique_id: kitchen_extractor_Spot
   name: "Kitchen Extractor Spot"
   payload_on: '{"Spot": 125 }'
   payload_off: '{"Spot":0}'
   state_topic: "kitchen_extractor/state"
   brightness_state_topic: "kitchen_extractor/state"
   command_topic: "kitchen_extractor/cmd"
   brightness_command_topic: "kitchen_extractor/cmd/speed"
   availability_topic: "kitchen_extractor/lwt"
   state_value_template: >
           {% if value_json.Spot > 9 %} {"Spot": 125 } {% else %} {"Spot":0} {% endif %}
   brightness_value_template: '{{value_json.Spot}}'
   brightness_command_template: '{"Spot": brightness }'
   brightness_scale: 250
   payload_available: "Online"
   payload_not_available: "Offline"
   optimistic: false
   qos: 0
   retain: false

Sniffing MQTT I got this message [kitchen_extractor/cmd {“Fan”: brightness ]
“brightness” instead of integer value

What do I wrong ?