Why cannot use Ishelluihelper?

I use this function and want to use the IE's Add Favorite Dialog but it
didn't work it always says "Cannot support the Interface"
but the AddChannel function is OK!
I check the MSDN & MSDN Online it has different desc:
MSDN:
 HRESULT AddFavorite(
    BSTR strURL,
    VARIANT Title
);
MSDN Online
HRESULT AddFavorite(
    BSTR URL,
    VARIANT *Title
);

What can I do please help me! Thank you!

procedure AddFavorite(aUrl, aTitle: string);
const CLSID_ShellUIHelper:TGUID=
  '{64AB4BB7-111E-11D1-8F79-00C04FC2FBE1}';
Var
   shelluihelper:Ishelluihelper;
   url,title:olevariant;
begin
  url:= aUrl;
  title:= aTile;
  shelluihelper:=createcomobject(CLSID_ShellUIHelper) as IshellUIHelper;
  shellUihelper.addfavorite(url,title);
end;