I just wanted to create very simple example of DataTriggers and animation. Two checkboxes and Rectangle. Checking the first cb makes the rectangle fade away. (CodeBehind var is true) Checking the second cb makes the rectangle come back. (var is false)

App is loading - the rectangle is showing (true) Firs cb is checked by default. I'm checking second cb - rect is dissapearing. It's OK. But when I then check the first cb rect isn't showing up. But checking the second cb still makes rect show up and fade away. here's my xaml and code behind:

<StackPanel>
    <RadioButton IsChecked="True" Checked="RadioButton_Checked"></RadioButton>
    <RadioButton Checked="RadioButton_Checked_1"></RadioButton>

    <Rectangle Name="r1" Width="100" Height="300" Fill="Green">
        <Rectangle.Style>
            <Style TargetType="Rectangle">
                <Style.Triggers>
                    <DataTrigger Binding="{Binding Active}" Value="True">
                        <DataTrigger.EnterActions>
                            <BeginStoryboard>
                            <Storyboard>
                                <DoubleAnimation
                                     Storyboard.TargetProperty="Opacity"
                                     From="0" To="1" Duration="0:0:1" 
                                     />
                            </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.EnterActions>
                    </DataTrigger>

                    <DataTrigger Binding="{Binding Active}" Value="False">
                        <DataTrigger.EnterActions>
                            <BeginStoryboard>
                                <Storyboard>
                                    <DoubleAnimation
                                     Storyboard.TargetProperty="Opacity"
                                     From="1" To="0" Duration="0:0:1" 
                                     />
                                </Storyboard>
                            </BeginStoryboard>
                        </DataTrigger.EnterActions>
                    </DataTrigger>

                </Style.Triggers>
            </Style>
        </Rectangle.Style>
    </Rectangle>

</StackPanel>


public bool Active
  {
     get { return (bool) GetValue(ActiveProperty); }
     set { SetValue(ActiveProperty, value); }
  }
  public static readonly DependencyProperty ActiveProperty =
      DependencyProperty.Register("Active", typeof(bool), typeof(MainWindow), new UIPropertyMetadata(false));


  private void RadioButton_Checked(object sender, RoutedEventArgs e)
  {
      Active = true;
  }

  private void RadioButton_Checked_1(object sender, RoutedEventArgs e)
  {

      Active = false;

  }