Hello to all the community.
I'm writing this since I'm encountering errors when I launch my custom
controllers written for a KUKA LWR arm, used in combination with Gazebo
simulator. The error comes when I run the roslaunch command which loads
such controllers.

*[ERROR] [1421148091.366974261, 5.814000000]: Could not load class
kuka_controllers/BacksteppingController: Failed to load library
/home/enrico/catkin_ws/devel/lib//libkuka_controllers.so. Make sure that
you are calling the PLUGINLIB_EXPORT_CLASS macro in the library code, and
that names are consistent between this macro and your XML. Error string:
Could not load library (Poco exception =
/home/enrico/catkin_ws/devel/lib//libkuka_controllers.so: undefined symbol:
_ZN26forward_command_controller24ForwardCommandControllerIN18hardware_interface20EffortJointInterfaceEE8startingERKN3ros4TimeE)*
*[ERROR] [1421148091.367239553, 5.814000000]: Could not load controller
'BacksteppingController' because controller type
'kuka_controllers/BacksteppingController' does not exist.*
*[ERROR] [1421148091.367296142, 5.814000000]: Use 'rosservice call
controller_manager/list_controller_types' to get the available types*

The weird thing is that running the command suggested by ROS (rosservice
call [...]) it actually returns all my controllers names. This error has
been introduced after the last ROS software updates and before that it was
working just fine. Also I have a call to PLUGINLIB_EXPORT_CLASS in my
source, so it is not that the problem.

As a note, the ROS built-in position controllers work, so it seems like a
linking or a parsing error.

Thanks in advance,
Enrico C.