Gazebo tutorial: follower plugin not working

Hi, i was teaching myself Gazebo based on this tutorial from the official site:

The goal was to get the robot to follow the cube, using the plugin libFollowerPlugin.so, but it seems that the robot is moving away from it.
video_castor

Can i know where i went wrong?

Hi,

When you set the the Roll angle of the wheel pose instead of 1.5707 try -1.5707