We assume that you grasped the way that ProB setups up the initial states of a B machine as outlined in Tutorial Setup Phases.
In this lesson, we examine what can go wrong in these phases and how one can find a solution. Indeed, setting up the constants and initial values of a machine is often the most difficult step for an animator. Unfortunately, it is also the very first step an animator has to perform.
First, open the machine "Jukebox.mch" which can be found in the SchneiderBook/Jukebox_Chapter13 subdirectory of the ProB Examples folder.
The main ProB window should look more or less as follows: