Multiple vehicle spawn error in ROS2 condition

Hello everyone,

I’m trying to spawn muliple iris_depth_camera vehicle in SITL
I followed below document.

When I tried to build that, I met the error

software versions are below.

gazebo version : classic
ROS2 version : ROS2 humble
PX4 version : 1.14.0 stable

Please give me any advice or ideas to solve the problem.
Thank you.