gazebo_msgs.msg import * ImportError: No module named msg, while trying to roslaunch to psawn urdf robots

edit

I am trying to spawn an already built .urdf file using ros launch, according to the tutorial in http://gazebosim.org/tutorials?tut=ro...

I have getting the error:

 rosrun gazebo_ros spawn_model -file `rospack find cnbiros_wheelchair`/model/wheelchair.urdf -urdf -z 1 -model wheelchair
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/gazebo_ros/spawn_model", line 26, in <module>
    from gazebo_ros import gazebo_interface
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/gazebo_ros/gazebo_interface.py", line 9, in <module>
    from gazebo_msgs.msg import *
ImportError: No module named msg

I have already installed gazebo_msgs using sudo apt-get install ros-kinetic-gazebo-msgs

Please help to solve this.