Rostopic echo /mavros/mission/waypoints Not working as expeted

Hi px4 lovers,
I am working on a ROS based wheeled robot to use the capabilities of PX4 for GPS waypoint navigation. And my Robot moves if a send velocity commands on /cmd_vel, so I do not want any actuator control from pixhawk, I want to use pixhawk as a sensor and interface(QGC) source.
** Plan**
I will subscribe to the waypoints from rostopic echo /mavros/mission/waypoints and also GPS and imu from mavros then I will simply use a general logic to move my robot to the first GPS location then to next (from /mavros/mission/waypoints).

when I do rostopic echo /mavros/mission/waypoints , i am getting some points, then if i create a new plan I am not getting them on this topic.
with the new plan, when I do for start mission, I am getting this error “Unable to start mission: Vehicle failed to change to Auto mode.”
But somehow I am not getting waypoints on /mavros/mission/waypoints topic .

I am new to these things, can you guide me how to do it

From the images it looks like you’re using ArduPilot. What firmware version are you using?