[gnome-db] sql statement not parsed correctly (postgresql)

this sql

(SELECT data FROM mezzo_chilometraggi
WHERE status <> 'E' AND id_mezzi = 4 AND data = '2011-01-01' LIMIT 1)
UNION
(SELECT data FROM mezzo_chilometraggi
WHERE status <> 'E' AND id_mezzi = 4 AND data < '2011-01-01' ORDER BY  
data DESC LIMIT 1)

is not parsed correctly; the result is without parenthesis that  
delimit queries before and after union

thanks in advance