Docker error ERROR: Cannot load message class for [livox_ros_driver2/CustomMsg]. Are your messages built?

[crazy-robotics]

I build livox_ros_driver2 in docker and on rostopic list i got

mubashir@mubashir:~$ rostopic list 
/livox/imu
/livox/lidar
/rosout
/rosout_agg

on `rostopic echo /livox/imu I got the following message

mubashir@mubashir:~$ rostopic echo /livox/lidar
ERROR: Cannot load message class for [livox_ros_driver2/CustomMsg]. Are your messages built?

I check online posts say build the workspace I have done it twice

[georgflick]

are you also sourcing that workspace in your terminal?

[crazy-robotics]

Yes, I source both root installation source /opt/ros/noetic/setup.bash and workspace source my_workspace/devel/setup.bash