ROS and Gazebo simulator with Pioneer-3at

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Hi, I followed this tutorial (https://www.youtube.com/watch?v=Yp92L...) for setting up Gazebo simulator with Pioneer-3at and command 'roslaunch example-pioneer3at-terrainworld.launch' works normally. When I type "rostopic pub -1 /cmd_vel geometry_msgs/Twist '[0.35, 0, 0]' '[0, 0, 0.7]'" or any of rostopic commands they do on the video nothing happens in the simulator, robot doesn't move, even when there is same output in the terminal as they get on the video. I am using Kinetic version of ROS. Am I missing something? Can someone help me? Thanks in advance.