Effect on Frame not working

Hi,

I'am trying to achieve an gradient background effect for layout controls. On a grid control it works like a charm. But on a Frame the OnAttached handler is not executed allthough the effect has been attached.

Thanks in advance.

 public class BackgroundGradientEffect : PlatformEffect
    {
        protected override void OnAttached()
        {
            try
            {
                this.UpdateGradient();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Cannot set property on attached control. Error: ", ex.Message);
            }
        }

        protected override void OnElementPropertyChanged(PropertyChangedEventArgs args)
        {
            if (args.PropertyName == GradientEffect.StartColorProperty.PropertyName || args.PropertyName == GradientEffect.EndColorProperty.PropertyName)
            {
                this.UpdateGradient();
            }
        }

        private void UpdateGradient()
        {
            Color startColor = GradientEffect.GetStartColor(this.Element);
            Color endColor = GradientEffect.GetEndColor(this.Element);
            GradientDrawable gradientDrawable = new GradientDrawable(GradientDrawable.Orientation.TopBottom, new []{ startColor.ToAndroid().ToArgb(), endColor.ToAndroid().ToArgb()});
            Container.Background = gradientDrawable;
        }

        protected override void OnDetached()
        {
        }
    }

 public static class GradientEffect
    {

        public static readonly BindableProperty HasGradientProperty =
            BindableProperty.CreateAttached("HasGradient", typeof(bool), typeof(GradientEffect), false, propertyChanged: OnHasGradientChanged);
        public static readonly BindableProperty StartColorProperty = BindableProperty.CreateAttached("StartColor", typeof(Color), typeof(GradientEffect), Color.Default);
        public static readonly BindableProperty EndColorProperty = BindableProperty.CreateAttached("EndColor", typeof(Color), typeof(GradientEffect), Color.Default);

        private static void OnHasGradientChanged(BindableObject bindable, object oldValue, object newValue)
        {
            var view = bindable as View;
            if (view == null)
                return;

            var hasGradient = (bool)newValue;
            if (hasGradient)
            {
                view.Effects.Add(new BackgroundGradientEffect());
            }
            else
            {
                var toRemove = view.Effects.FirstOrDefault(e => e is BackgroundGradientEffect);
                if (toRemove != null)
                    view.Effects.Remove(toRemove);
            }
        }



        public static Color GetStartColor(BindableObject view)
        {
            return (Color)view.GetValue(StartColorProperty);
        }

        public static void SetStartColor(BindableObject view, Color value)
        {
            view.SetValue(StartColorProperty, value);
        }

        public static Color GetEndColor(BindableObject view)
        {
            return (Color)view.GetValue(EndColorProperty);
        }

        public static void SetEndColor(BindableObject view, Color value)
        {
            view.SetValue(EndColorProperty, value);
        }
    }

    public class BackgroundGradientEffect : RoutingEffect
    {
        public BackgroundGradientEffect() : base("Blub.BackgroundGradientEffect")
        {
        }
    }

Regards