Hokuyo Senser not working

Hi, I am using ROS kinetic and Gazebo 7.8.1 I want to connect Hokuyo sensor to Turtlebot. I can see a box representing Hokuyo sensor on the Turtlebot but the sensor is not scanning the world. Here is my specification **kobuki_hexagons_kinect_hokuyo.urdf.xacro file** **hokuyo.urdf.xacro file** **turtlebot_gazebo_brass.urdf.xacro file** 0 0 0 0 0 0false407201-1.5707961.5707960.1030.00.01Gaussian0.00.01/hokuyo_laserbase_laser_link