Для нестатического поля требуется ссылка на объект

 Ошибка в : BlurEffect.BeginAnimation(BlurEffect.RadiusProperty, animation); 

 internal OverlayState CurrentOverlaySelection; 
 
public enum OverlayState 
{ 
    None, 
    Manager, 
    License 
} 
private void SwitchOverlay(OverlayState OverlayState) 
{ 
    if (CurrentOverlaySelection != OverlayState) 
    { 
        DoubleAnimation animation = new DoubleAnimation 
        { 
            To = 2.0, 
            Duration = TimeSpan.FromSeconds(0.25), 
            EasingFunction = new QuarticEase() 
        }; 
        DoubleAnimation animation2 = new DoubleAnimation 
        { 
            To = 1.0, 
            Duration = TimeSpan.FromSeconds(0.25) 
        }; 
        switch (OverlayState) 
        { 
            case OverlayState.License: 
                LicenseOverlayContainer.IsHitTestVisible = true; 
                LicenseOverlayContainer.BeginAnimation(UIElement.OpacityProperty, animation2); 
                break; 
        } 
        BlurEffect.BeginAnimation(BlurEffect.RadiusProperty, animation); 
        CurrentOverlaySelection = OverlayState; 
    } 
}