Mqtt light - status not working

I created a mqtt light entity but the status is not displayed. What am I doing wrong?

mqtt:
 - light:
   - name: "light22"
     unique_id: mqtt-iR2fO9eJ7dW8zX3jL6kX222
     object_id: mqtt-D1_D2_6_L22
     state_topic: "D1/out/cron/A21"
     state_value_template: "{% if value_json.data[14] == 0 -%}OFF{%-else-%}ON{%-endif%}"
     command_topic: "D1/in"
     payload_on: '{"serial_port":"/dev/USB_DconBus_1","port":0,"address":21,"cmd":"#15A001"}'
     payload_off: '{"serial_port":"/dev/USB_DconBus_1","port":0,"address":21,"cmd":"#15A000"}'
     optimistic: false