Are your path_tracks properly linked?
You need to have an entity called team_trainwatcher(or something like that) and make sure that the flag marked "Train watcher controls movement" is checked.
You could just give us a VMF and we could find it out without just guessing at random.
From the vmf. file, I'd say that the issue is no track_56 entity
Your final path_track (track_55) has Next Stop Target set to track_56 which doesn't exist. Also, your second to last track (track_54) needs to have the outputs listed here
Try to fix those and see if it works
Wild guesses:
-You didn't use boojum's examples