Update BuiltinDocumentProperties

[Blackpower]

Im trying to update some BuiltinDocumentProperties of office documents.
It all goes wel, except that it doesnt save the properties.
If I save to a new file the new properties are saved as well.

here is the code.

use strict;
use Win32::OLE qw(in);

my $Word = Win32::OLE->new('Word.Application', 'Quit');
my $Doc = $Word->Documents->Open('Document1.doc');

$Doc->BuiltinDocumentProperties->{Title} = "Custom Title" ;
$Doc->BuiltinDocumentProperties->{Comments} = "Custom Comment" ;


#$Doc->SaveAs( 'Document2.doc'); # this works

$Doc->Save ; #this doesnt work.

$Doc->Quit ;