items.items ????

hvordan får jeg nu dette til at virke?:

ShowMessage(sub.items[number].items[numberi].description);

i den nye Subsubitem skal der være disse strings:

description
title
url

jeg har denne kode i forvejen:

type
tsubitem = class(TCollectionItem)
  public
   url,title: string;
  end;

  tsubscripts = class(TCollection)
   function getitem(index: integer): tsubitem;
   constructor create;
  public
   function add: tsubitem; overload;
   procedure add(title, url: string); overload;
   property items[index: integer]: tsubitem read getitem;
  end;
//////////////////////
function tsubscripts.getitem(index: integer): tsubitem;
begin
   result := inherited getitem(index) as tsubitem;
end;

function tsubscripts.add: tsubitem;
begin
   result := inherited add as tsubitem;
end;

procedure tsubscripts.add(title, url: string);
var a: tsubitem;
begin
   a := add;
   a.title := title;
   a.url := url;
end;

constructor tsubscripts.create;
begin
   inherited create(tsubitem);
end;