i I followed the kivymd 1.1.1 docs for how to make a list and add an item to it and i spent to days trying to fix the it and i did not found any solution that is my code what’s the problem in the code

from kivymd.app import MDApp 
from kivy.lang import Builder
from kivy.uix.screenmanager import ScreenManager, Screen
from kivymd.uix.list import IRightBodyTouch, ThreeLineAvatarIconListItem
from kivymd.uix.pickers import MDDatePicker
from kivymd.uix.selectioncontrol import MDCheckbox
from kivy.properties import StringProperty


class TaskScreen(Screen):pass

class AddTask(Screen):pass

class Manager(ScreenManager):pass

class ListItemWithCheckbox(ThreeLineAvatarIconListItem):
    """'''Custom list item.'''
    The list item will be added to the task list"""
    icon = StringProperty("android")

class RightCheckbox(IRightBodyTouch, MDCheckbox):
    '''Custom right container.'''


class TasksApp(MDApp):
    # def __init__(self, **kwargs):
    #     super().__init__(**kwargs)
    def add_task(self,title, task, date):
        title = self.root.ids.add_task.ids.title.text
        task = self.root.ids.add_task.ids.task.text
        date = self.root.ids.add_task.ids.date.text
        task_item =ListItemWithCheckbox(text=title,
                                        secondary_text=task,
                                        tertiary_text=date,
                                        )
        self.root.ids.task_screen.ids.container.add_widget(task_item)
        
        self.clean_fields(title,task,date)

    def clean_fields(self,title,task,date):
        self.root.ids.add_task.ids.title.text = ''
        self.root.ids.add_task.ids.task.text = ''
        self.root.ids.add_task.ids.date.text = ''
    
    def open_date_picker(self):
        date_dialog = MDDatePicker()
        date_dialog.bind(on_save=self.on_save)
        date_dialog.open()
    
    def on_save(self, instance, value, date_range):
        value = value.strftime('%A %d %B %Y')
        self.root.ids.add_task.ids.date.text = str(value)
    
    def remove_item(self,task_item):
        self.root.ids.task_screen.ids.container.remove_widget(task_item)
        
    
    def build(self):
        self.theme_cls.primary_palette = 'Teal'
        return Builder.load_file('tasks.kv')


TasksApp().run()

and the kv file:

#: import CardTransition kivy.uix.screenmanager.CardTransition
#: import datetime datetime
# :set date_text datetime.now().strftime('%A %d %B %Y')


Manager:
    id:sm
    TaskScreen:
        id: task_screen
    AddTask:
        id: add_task

<TaskScreen>:
    name: 'task_screen'
    MDFloatLayout:
        orientation:'vertical'
        MDLabel:
            text: "[size=40][u][b]Tasks[/b][/u][/size]"
            color: 'teal'
            markup:True
            halign: 'center'
            pos_hint: {'center_x': 0.5,'center_y': 0.95}
        MDLabel:
            id: date_now
            text:str(datetime.datetime.now().strftime('[b][size=25]Today: [/size][/b][b][size=20]%A %d %B %Y -%I:%M[/size][/b]'))
            color: 'teal'
            markup:True
            halign: 'center'
            pos_hint: {'center_x': 0.5,'center_y': 0.88}

    ScrollView:
        MDList:
            id: container

    MDFloatingActionButton:
        elevation:3
        icon: 'plus-outline'
        pos_hint: {'center_x': 0.5,'center_y': 0.09}
        on_release:
            # app.root.transition.direction = 'left'
            app.root.transition = CardTransition(mode='pop')
            app.root.current = 'add_task'

<AddTask>:
    name: 'add_task'

    MDLabel:
        text: "[size=40][u][b]Add Task[/b][/u][/size]"
        color: 'teal'
        markup:True
        halign: 'center'
        pos_hint: {'center_x': 0.5,'center_y': 0.95}

    MDLabel:
        id: date_now
        text:str(datetime.datetime.now().strftime('[b][size=25]Today: [/size][/b][b][size=20]%A %d %B %Y - %I:%M[/size][/b]'))
        color: 'teal'
        markup:True
        halign: 'center'
        pos_hint: {'center_x': 0.5,'center_y': 0.88}
    MDLabel:
        id: date
        text: '[u][size=15]___[/size][/u]'
        color: 'teal'
        markup:True
        pos_hint: {'center_x': 0.65,'center_y': 0.75}
    MDIconButton:
        icon:'calendar-multiselect'
        icon_size:'48sp'
        theme_icon_color: "Custom"
        icon_color: app.theme_cls.primary_color
        pos_hint: {'center_x':0.75,'center_y': 0.75}
        on_release: app.open_date_picker()

    MDLabel:
        text: "[size=20][u][b]Title[/b][/u][/size]"
        color: 'teal'
        markup: True
        pos_hint: {'center_x': 0.65,'center_y': 0.6}

    MDTextField:
        id: title
        pos_hint:{"center_x": 0.5,'center_y': 0.5}
        size_hint_x: 0.7
        max_text_length: 20
        font_size: 20
        bold:True

    MDLabel:
        text: "[size=20][u][b]Enter Task[/b][/u][/size]"
        color: 'teal'
        markup:True
        pos_hint: {'center_x': 0.65,'center_y': 0.4}

    MDTextField:
        id: task
        pos_hint:{"center_x": 0.5,'center_y': 0.3}
        size_hint_x: 0.7
        max_text_length:60
        font_size:19
        bold:True

    MDRaisedButton:
        text:'Save'
        pos_hint:{"center_x": 0.72,'center_y': 0.15}
        on_release:
            app.add_task(title, task, date)
            app.root.transition = CardTransition(mode='pop')
            app.root.current = 'task_screen'

    MDIconButton:
        icon: 'arrow-u-right-top'
        icon_size:'48sp'
        theme_icon_color: "Custom"
        icon_color: app.theme_cls.primary_color
        pos_hint:{'center_x':0.5,'center_y': 0.15}
        on_release:
            # app.root.transition.direction = 'right'
            app.root.transition = CardTransition(mode='pop')
            app.root.current = 'task_screen'
            app.clean_fields(title, task, date)

<ListItemWithCheckbox>:
    id: task_item


    RightCheckbox:
        id : checbox

    IconLeftWidget:
        icon: 'trash-can-outline'
        theme_text_color: "Custom"
        text_color: 'teal' #1, 0, 0, 1
        on_release:app.remove_item(task_item)

and the pic for the app to icons and to check boxes

search on the web reading docs try to change the list items and positions of widgets and check for any code mistakes or typo ….