Bot.register_next_step_handler doesn't work automatically. Why?

Question

Python

Exit the calendar online. The user selects a date, notifications will appear that the date has been selected. But after that, the following code does not run. bot.register_next_step_handler doesn't help. It will work when the user sends something to the bot.

@bot.callback_query_handler(func=lambda call: call.data[0:13] == 'calendar-day-')
def get_day(call):
    chat_id = call.message.chat.id
    saved_date = current_shown_dates.get(chat_id)
    if(saved_date is not None):
        day=call.data[13:]
        date = datetime.datetime(int(saved_date[0]),int(saved_date[1]),int(day))
        msg = bot.send_message(chat_id, str(date))
        bot.answer_callback_query(call.id, text="Дата выбрана")
        bot.register_next_step_handler(msg, person)

    else:
        #Do something to inform of the error
        pass
    bot.register_next_step_handler(msg, person)

def person(message):
    keyboard = types.ReplyKeyboardMarkup(resize_keyboard=True, row_width=0.2)
    keyboard.add(*[types.KeyboardButton(name) for name in ["1", "2", "3", "4", "5", "6"]])
    keyboard.add(*[types.KeyboardButton(name) for name in ["Главное меню"]])
    mess = bot.send_message(message.chat.id, "Укажите количество персон:", reply_markup=keyboard)
    bot.register_next_step_handler(mess, answer)

Now if the user writes something, then def person(message):
And I need that he immediately (automatically) earned after the notification "Date selected".
How to fix, Help! Thank you!