SlimDX Почему сцена не очищается в празрачный цвет?

[gordon.freeman]

 public Overlay() {        
           
            form = new Form();
            form.BackColor = Color.IndianRed;
            form.TransparencyKey = Color.IndianRed;

            m_Factory = new Factory(FactoryType.Multithreaded);
            WindowRenderTargetProperties properties = new WindowRenderTargetProperties();
            properties.PresentOptions = PresentOptions.None;
            properties.Handle = form.Handle;
            properties.PixelSize = new Size(form.Width, form.Height);

            props = new RenderTargetProperties();
            props.PixelFormat = new PixelFormat(SlimDX.DXGI.Format.B8G8R8A8_UNorm, AlphaMode.Premultiplied);
            props.MinimumFeatureLevel = FeatureLevel.Default;
            props.Type = RenderTargetType.Hardware;
            props.Usage = RenderTargetUsage.None;
            props.MinimumFeatureLevel = FeatureLevel.Default;

            m_RenderTarget = new WindowRenderTarget(m_Factory, props, properties);
     }

  public void RenderScene(){

   while(true){
                    m_RenderTarget.BeginDraw();
                    m_RenderTarget.Clear(new Color4(255, Color.Transparent.R, Color.Transparent.G, Color.Transparent.B));


                    m_RenderTarget.DrawRectangle(m_BrushRed, new Rectangle(0, 0, 100, 100));
                    m_RenderTarget.EndDraw();
       }

  }

Сейчас по неизвестным мне причинам, метод Clear чистит все в белый