allow_unknown parameter ignored

Hi there, I want to avoid the global planner to plan its paths through the unknown because it is not working for my case. So as described [here](http://wiki.ros.org/navfn) I set the paramter allow_unknown to false. So I created a yaml named **global_planner.yaml** file like this: NavfnROS: allow_unknown: false default_tolerance: 5 In the launch file for the move_base node I added a line to load the parameters: The parameter also shows up in the parameter server: rosparam get /move_base/NavfnROS/allow_unknown returns **false**, as expected. So, whats wrong here??? Thanks for any help! Micha