[Python] Почему определение изменений в беседе не работает?

longpoll = VkLongPoll(vk_session)

    for event in longpoll.listen():

        if event.type == VkEventType.CHAT_EDIT:
            if event.type_id == 1:
                msg='a'
                      
            if event.type_id == 6:
                msg='c'
                     
            if event.type_id == 7:
                msg='c'
                        
            if event.type_id == 8:
                msg='b'

            vk.messages.send(
                chat_id=event.chat_id,
                message=msg
                )
            print(msg)