Delphi how to add transparent layers to TImage32

Question

I need to be able to add transparent PNG images as layers to a ImgView32 (from graphics32 library). Does anybody know how can this be achieved?

Basically, I can add any image as a layer to my Image32, but all images (even if they are transparent by nature) have a white background. I need to workaround this problem. Does anybody have any idea?

This is how I add my image as a layer:

var
  B: TBitmapLayer;
  P: TPoint;
  W, H: Single;
const
  MasterAlpha: SmallInt = 100;
begin
  with OpenPictureDialog do
    if Execute then
    begin
      B := TBitmapLayer.Create(ImgView321.Layers);
      with B do
      try
        Bitmap.LoadFromFile(FileName);
        Bitmap.DrawMode := dmTransparent;
        with ImgView321.GetViewportRect do
          P := ImgView321.ControlToBitmap(GR32.Point((Right + Left) div 2, (Top + Bottom) div 2));
        W := Bitmap.Width * 0.5;
        H := Bitmap.Height * 0.5;

        with ImgView321.Bitmap do
          Location := GR32.FloatRect(P.X - W, P.Y - H, P.X + W, P.Y + H);

        Scaled := True;
        B.Bitmap.CombineMode := cmBlend;
        B.Bitmap.DrawMode := dmTransparent;
        OnMouseDown := LayerMouseDown;
        OnKeyUp :=LayerKeyUp;
      except
        Free;
        raise;
      end;
      Selection := B;
    end;
end;

So it does not seem to matter that I set Bitmap.DrawMode := dmTransparent; it does nothing. Even if I added PNGImage to uses, nothing changes except I now can pick png images to add to my image

So please tell me what I am doing wrong and what should I do to solve this.

Thank you

EDIT

I am aware of Loading PNG into Bitmap32, as described in this link http://graphics32.org/wiki/FAQ/ImageFormatRelated but apparently I "cannot assign a TBitmap32 to a TBitmapLayer" so after loading the transparent PNG into a Bitmap32 just fine (in theory) how do I assign it to my layer?