Watermark on FastReport

procedure TfrmMenu.frxReport1EndDoc(Sender: TObject);
var
  p: TfrxReportPage;
  i: integer;
begin
  frxReport1.Preview.Lock;
  for i := 0 to frxReport1.PreviewPages.Count - 1 do
  begin
    p:=TfrxReportPage(frxReport1.PreviewPages.Page[i]);
    p.BackPicture.LoadFromFile(ExtractFilePath(Application.ExeName)+'watermark.png');
    p.BackPictureVisible:=True;
    p.BackPicturePrintable:=True;
    frxReport1.PreviewPages.ModifyPage(i,p);
  end;
  frxReport1.Preview.UnLock;
end;