uORB doesn't show the topic "actuator_controls"

I would like to control my Pixhawk actuators using ROS2. When I use the MAVLink console to review the topics on the Pixhawk, I find that the uORB topic “actuator_controls_0” is not subscribed, so I can’t publish from ROS2 using micrortps_agent.

Does anyone have any idea what the solution might be? Thanks!