Why doesn't Binding work?

Question

WPF

There is a ViewModel that describes the fields and methods that return them.
Fragment:

public OrdersListViewModel()
        {
            base.DisplayName = "Список заказов";
            Dat1 = DateTime.Now.AddDays(-7).Date;
            Dat2 = DateTime.Now.AddDays(3).Date;
        }

        private ObservableCollection<ViewOrderHeader> _ViewOrdelHeaderCollection;
        private DateTime _dat1;
        
       public ObservableCollection<ViewOrderHeader> ViewOrdelHeaderCollection
        {
           ...
        }

        public DateTime Dat1
        {
            get     { return _dat1;   }
            set      { _dat1 = value;    base.OnPropertyChanged("Dat1");    }
        }
     
        }

Now I display the data on the View:

<TextBlock  Text="{Binding Path=Dat1}"  /> <!--биндинг работает!!!-->
        <DataGrid ItemsSource="{Binding}" >
            <DataGrid.Columns>
                     <DataGridTextColumn>
                    <DataGridTextColumn.Header>
                        <Expander Header="Дата заказа">
                            <StackPanel Orientation="Vertical" DataContext="{Binding}">
                                <DatePicker x:Name="dpZ1A" 
                                            DisplayDate="{Binding Path=Dat1}" /> <!--Binding Не работает-->
                            </StackPanel>
                        </Expander>
                    </DataGridTextColumn.Header>
                </DataGridTextColumn>
          </DataGrid>

As it was already written above, Binding does not work everywhere. Please explain where I went wrong and how to fix it?

Answer 1

Top {Binding Path=Dat1}, bottom {Binding Path=Dt1}. Typo - missing character a.
When you run the program in the studio, diagnostic messages are often displayed in the Output window, and similar errors are displayed there.