SQL request change when upgrade from 7.0.2 to 7.1.3

Hello,

Recently, I have upgraded my postgresql server from 7.0.2 to 7.1.3. But,
now, one request which was 'good' before, don't want to work any more
now.

It was : (pretty long)

SELECT aes.ent_id, e.type, e.nom, aes.sect_id as voulu,
cvd_new(current_date, e.date_entree, 'new') FROM ass_entrep_sectact aes,

entreprise e WHERE e.id = aes.ent_id and aes.sect_id <> 3 and
aes.sect_id <> 9
and aes.sect_id <> 1 and aes.sect_id <> 13 and aes.sect_id = 56
UNION
SELECT distinct on (aes.ent_id) aes.ent_id, e.type, e.nom, aes.sect_id,
cvd_new(current_date, e.date_entree, 'new') FROM ass_entrep_sectact aes,

entreprise e WHERE e.id = aes.ent_id and aes.sect_id <> 3 and
aes.sect_id <> 9
and aes.sect_id <> 1 and aes.sect_id <> 13 and aes.sect_id <> 56 and
aes.ent_id
not in (SELECT ent_id FROM ass_entrep_sectact WHERE sect_id = 56 and
sect_id <> 3
and sect_id <> 9 and sect_id <> 1 and sect_id <> 13) ORDER BY e.type,
e.nom

Now, if I want that my request works well, I have to remove the order by
statement. But, of course, it is not ordered any more.

So how can I translate this request to one which can work with an order
by statement ?

Thanks.

--
Richard NAGY
Presenceweb