Can't attach plugin with roslaunch

My world file (adapted from the [tutorial](http://gazebosim.org/tutorials?cat=guided_i&tut=guided_i5)) contains a plugin : model://car2 The plugin loads and displays the expected message when I do this : $ export GAZEBO_MODEL_PATH="$CATKIN_WS/src/tas_group_2/car_gazebo/models" $ export GAZEBO_PLUGIN_PATH="$CATKIN_WS/src/tas_group_2/car_gazebo/plugins/" $ gazebo worlds/car.world However I can't get it to launch through roslaunch with : $ roslaunch car_gazebo car.launch Gazebo displays no error and the simulation seems to run. The problem is the plugin doesn't seem to run. My files contain : package.xml (car_gazebo) : car_gazebo ...gazebo_rosgazebo_roscatkin car.launch : I thought the two methods where equivalent. Any idea how to get the plugin to work with the roslaunch command? Cheers