i am trying to run Hector quadrotor demo. from this tutorial

wiki.ros.org/hector_quadrotor/Tutorials/Quadrotor%20outdoor%20flight%20demo

i am getting this error when i run the command below

roslaunch hector_quadrotor_demo outdoor_flight_gazebo.launch

... logging to /home/neo/.ros/log/447c986a-2550-11e3-9561-87d85f24eea4/roslaunch-ubuntu-17732.log Checking log directory for disk usage. This may take awhile. Press Ctrl-C to interrupt Done checking log file disk usage. Usage is <1GB.

Traceback (most recent call last): File "/opt/ros/groovy/stacks/xacro/xacro.py", line 35, in xacro.main() File "/opt/ros/groovy/stacks/xacro/src/xacro.py", line 554, in main processincludes(doc, os.path.dirname(sys.argv[1])) File "/opt/ros/groovy/stacks/xacro/src/xacro.py", line 202, in processincludes raise XacroException("included file \"%s\" could not be opened: %s" % (filename, str(e))) xacro.XacroException: included file "/home/neo/hectorquadrotortutorial/hectorquadrotor/hectorquadrotorgazebo/urdf/quadrotorplugins.gazebo.xacro" could not be opened: [Errno 2] No such file or directory: '/home/neo/hectorquadrotortutorial/hectorquadrotor/hectorquadrotorgazebo/urdf/quadrotorplugins.gazebo.xacro' while processing /home/neo/hectorquadrotortutorial/hectorquadrotor/hectorquadrotorgazebo/launch/spawnquadrotor.launch: Invalid tag: Cannot load command parameter [robotdescription]: command [/opt/ros/groovy/stacks/xacro/xacro.py '/home/neo/hectorquadrotortutorial/hectorquadrotor/hectorquadrotordescription/urdf/quadrotorhokuyoutm30lx.gazebo.xacro'] returned with code [1].

Param xml is <param command="$(find xacro)/xacro.py '$(arg model)'" name="robot_description"/>