Calendar Control Event Issues in WPF C#

I'm trying to bind a TextBox to the selected date on a Calendar control, and when it initializes, there is no issue. The problem is that after, when I change the selected date, the TextBox remains at its initial value (today). I have tried 3 methods, including simply returning to TextBox.Text = Calendar.DisplayDate.ToString(), but the problem persists.

Does anybody know either what causes this, or a way around it?

Note that PropertyChanged is not null in Method 2.

My code is as follows, with the other two methods implemented:

XAML:

<Calendar Grid.Column="1" Height="170" HorizontalAlignment="Left" Name="calStart" VerticalAlignment="Top"  Width="180" IsTodayHighlighted="False" SelectedDatesChanged="CalStartSelectedDatesChanged">
            <Calendar.CalendarDayButtonStyle>
                <Style>
                    <Style.Triggers>
                    <DataTrigger Binding="{Binding Converter={StaticResource conv}}" Value="1">
                            <Setter Property="Button.Background" Value="LightGreen" />

                        </DataTrigger>
                </Style.Triggers>
                </Style>
            </Calendar.CalendarDayButtonStyle>
     </Calendar>
 <TextBox Height="23" HorizontalAlignment="Left" Margin="34,33,0,0" Text="{Binding StartBindProp, Mode=OneWay}" Name="txtStartDate" VerticalAlignment="Top" Width="120" Grid.Column="1" Grid.Row="1" />

C# Method 1:

private void CalStartSelectedDatesChanged(object sender, SelectionChangedEventArgs e)
    {
        StartBindProp = calStart.DisplayDate.ToString();
    }


    public string StartBindProp
    {
        get { return (string)GetValue(StartBindPropProperty); }
        set { SetValue(StartBindPropProperty, value); }
    }

    // Using a DependencyProperty as the backing store for StartBindProp.  This enables animation, styling, binding, etc...
    public static readonly DependencyProperty StartBindPropProperty =
        DependencyProperty.Register("StartBindProp", typeof(string), typeof(MainControl), new UIPropertyMetadata(""));

Method 2:

 private void CalEndSelectedDatesChanged(object sender, SelectionChangedEventArgs e)
    {
        EndBind = calEnd.DisplayDate.ToString();
    }

    private string m_EndBind = "endtest";


    public string EndBind
    {
        get { return m_EndBind; }
        set
        {
            m_EndBind = value;

            if (null != PropertyChanged)
            {
                PropertyChanged(this, new PropertyChangedEventArgs("EndBind"));
            }
        }
    }

Thanks for the help!

EDIT: The following xaml has the same issue (and apparently renders the calendar read-only):

<TextBox Text="{Binding ElementName=calStart, Path=DisplayDate, Mode=OneWay}" />

Use Calendar.SelectedDate (or SelectedDates if multiple) instead of DisplayDate

I believe the DisplayDate is used to determine which date has the "selected" outline around it in the calendar (since multiple dates can be selected), while SelectedDate is the actual value of the control.

You can find the MSDN docs on the Calendar control here