Armour is not working?

[Piethon]

If it doesn't work, maybe this will tell us why.

            if self.player.leather_chest_plate_on == True:
                print(self.player.leather_chest_plate_on)
                print(self.player.health)
                self.player.health -= ZOMBIE_DAMAGE - self.leather_chest_plate_protection
                print(self.player.health, ZOMBIE_DAMAGE, self.leather_chest_plate_protection)

Nothing got printed.