Simulating a Car like Robot in Gazebo

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Hi there, I am trying to simulate a car like robot in Gazebo and I found an example here and another example here. When I try the 1st example, I get the error :

[ERROR] [1439958135.355028687, 1.403000000]: No type element found for transmission joint_back_left_wheel_trans
[ERROR] [1439958135.355073512, 1.403000000]: No type element found for transmission joint_back_right_wheel_trans
[ERROR] [1439958135.355104844, 1.403000000]: No type element found for transmission joint_front_left_wheel_trans
[ERROR] [1439958135.355119397, 1.403000000]: No type element found for transmission joint_front_right_wheel_trans
[ INFO] [1439958135.454681337, 1.403000000]: Loaded gazebo_ros_control.

And my output looks like this:

And when I try the second example I get the error:

[ERROR] [1439959540.037343699, 1.196000000]: No type element found for transmission joint_back_left_wheel_trans
[ERROR] [1439959540.037397296, 1.196000000]: No type element found for transmission joint_back_right_wheel_trans
[ERROR] [1439959540.037432173, 1.196000000]: No type element found for transmission joint_front_left_wheel_trans
[ERROR] [1439959540.037466054, 1.196000000]: No type element found for transmission joint_front_right_wheel_trans

And my output looks like this:

Why am I getting such strange robots besides my Husky which looks completely fine ?