[Err] [Plugin.hh:178] Failed to load plugin libgazebo_light_sensor_plugin.so:

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Hello, I'm a beginner trying to follow this tutorial: https://robohub.org/create-a-ros-sens.... I'm using Ubuntu 18.04, ros melodic and gazebo 9, it's necessary to install the gazebo_ros_pkgs. The tutorial uses a camera sensor to get a image a then calculate the illuminance of the image, at the end it says:

Now launch the world. Be sure that a roscore is running or your machine, and that the GAZEBO_PLUGIN_PATH environment var includes the path to the new plugin.

But when I try runing roslaunch gazebo_light_sensor_plugin main.launch I get the next msg in the terminal:

[Msg] Waiting for master.
[Msg] Connected to gazebo master @ http://127.0.0.1:11345
[Msg] Publicized address: 192.168.1.3
[ INFO] [1585232434.291802849]: waitForService: Service [/gazebo/set_physics_properties] is now available.
[ INFO] [1585232434.318936454]: Physics dynamic reconfigure ready.

    [Err] [Plugin.hh:178] Failed to load plugin libgazebo_light_sensor_plugin.so: /home/yepez/catkin_ws/devel/lib/libgazebo_light_sensor_plugin.so: undefined symbol: _ZN6gazebo20GazeboRosCameraUtils13TriggerCameraEv

The $GAZEBO_PLUGIN_PATH is blank by default, but even if I change it for /home/yepez/catkin_ws/src/gazebo_light_sensor_plugin/include where the file .h is located, it still send me that error.

Thanks in advance to everyone for reading it.