Differential Drive Controller wouldn't work on another world file with multi turtlebots.

edit

So I'm just launching the file available in turtlebot3_gazebo/launch/multi_turtlebot3.launch as it is -- only changing the world file that I want to launch instead of default world file. No error is created however, with the launch of the third robot, I see no diff_drive_plugin is started due to which I'm unable to control the third turtlebot3. Any idea why it wouldn't turn on for the third robot in a new world file?

any help is greatly appreciated.