My 2000 Alhambra has remote central locks.....but both back doors are staying locked. The tailgate / both front doors & fuel cap are unlocking. The car battery did run flat and the remotes (20 started acting up so I re-coded them. Car LOCKS ok.......but when you press UNLOCK the interior light comes on and the turn signals flash.....but doors only unlock after a delay. The doors unlock with the key - but back doors remain locked. Scanned the memeory with VAG-COM and found no faults? Where should I start checking ?