[WPF] How to start a storyboard defined in a style?

XAML:

<Window.Resources><Style x:Key="GridStyle1" TargetType="{x:Type Grid}"><Style.Resources><Storyboard x:Key="Storyboard1"><ColorAnimationUsingKeyFrames Storyboard.TargetProperty="(Panel.Background).(SolidColorBrush.Color)" Storyboard.TargetName="{x:Null}"><EasingColorKeyFrame KeyTime="0:0:1" Value="Red"/></ColorAnimationUsingKeyFrames></Storyboard></Style.Resources><Setter Property="Background" Value="White"/></Style></Window.Resources><Grid x:Name="grid" Style="{DynamicResource GridStyle1}" MouseDown="Grid_MouseDown"/>

C# 1:

            Style style = this.Resources["GridStyle1"] as Style;
            Storyboard storyboard = style.Resources["Storyboard1"] as Storyboard;

            storyboard.Begin();

Exception:

C# 2:

        private void Grid_MouseDown(object sender, MouseButtonEventArgs e)
        {
            Style style = grid.Style;
            Storyboard storyboard = style.Resources["Storyboard1"] as Storyboard;

            storyboard.Begin();
        }

Exception:

Changing

            storyboard.Begin();

to

            storyboard.Begin(this);

results in no response of the app when pressed mouse down.

Note: The goal is to start a storyboard from code behind, not using triggers in XAML.