i just ran a similar query against a table holding 1:250k index map & it worked.
select sheet
from index250K
where contains (the_geom, GeometryFromText('POINT(100.65 13.85)', 4240))
i guess i'll try re-running the loader on that shapefle & try again.
btw i'm using the pgdev.306.jdbc3.jar thru coldfusion if that's of any
signifcance.