Unable to move Gazebo Robot

edit

Hi, I am trying chapter 9 of "ROS Robotics Projects".

roslaunch chefbot_gazebo chefbot_empty_world.launch

starts gazebo without error message.

in gazebo, the SimTime and RealTime is increasing.

rosrun chefbot_bringup chefbot_teleop_key

shows:

Control Your Turtlebot!
---------------------------
Moving around:
   u    i    o
   j    k    l
   m    ,    .

q/z : increase/decrease max speeds by 10%
w/x : increase/decrease only linear speed by 10%
e/c : increase/decrease only angular speed by 10%
space key, k : force stop
anything else : stop smoothly

... But i am unable to move the robot?

Any hint