CreateOleObject('Word.Application') - Dotx öffnen aber docx bekommen, wie?

[Delphi.Narium]

Delphi-Quellcode:

var
 doc : String;
begin
 doc := frm_main.AppPath + 'data\formulare\dokumentenname.docx';
 if FileExists(doc) then
 begin
   ShellExecute(0, 'open', PChar(doc), nil, nil, SW_NORMAL );
 end;