Hello everybody,

I tried to implement bots in my survey but I failed and don´t know how. I have another survey with the same tests.py code and it´s working fine.
My Bot-code:
class PlayerBot(Bot):
    def play_round(self):
        yield EXP
        if self.player.group.treatment:
            yield UnitsMix, dict(units=random.choice([0, 10])
                                )
        else:
            yield UnitsStraight, dict(units=random.choice([0, 10])
                                 )
    def app_after_this_page(self, upcoming_apps):
            return 'INFO'
            
 My init.py Code
 
 class EXP(Page):
    form_model = 'player'
    @staticmethod
    def before_next_page(player: Player, timeout_happened):
        #if (player.id_in_group % 2) == 0:
        if (player.group.id_in_subsession % 2) == 0:
            player.group.treatment = True
        else:
            player.group.treatment = False
            
 My warning if I try it:
 
 TypeError: group.treatment is None. Accessing a null field is generally considered an error. Or, if this is intentional, use field_maybe_none()
 
 
 There are no problems if I try it myself but I need the bots to test my app in a proper way.
 
 Thank you all in advance,
 
 Gregor