sending commands via MQTT

[MrKelser]

Hi, I have a question.
I need to turn on/off a relay via MQTT, I am using mosquitto broker.

mosquitto_pub -h localhost -p 1883 -t 'application/fe7bae52-4682-497c-a62c-7830637193e4/device/a8404152d185b432/command/down' -m '{"devEui":"a8404152d185b432","confirmed":true,"fPort":5,"data":"AwEB"}'

With this command, I can turn on the relay from the terminal, but subscribing from FUXA does nothing. I would like to activate it with a button, but I don't know how.