about subselect

Hi,
I make a subquery test at postgresql
7.3.3 and postgresql 8.0.3.
I found that postgresql 8.0.3 can't do this,
while at postgresql 7.0.3 it works quite well :
create table temp_hasil2(
nojob numeric,
nik numeric,
tanggal numeric,
kdpt numeric,
kdljr numeric
);

create table ap012(
nojob numeric,
tglavd numeric,
ptcd numeric
);

create table am382(
nojob numeric,
nik numeric,
tglavd numeric,
lkrjacd numeric
);

Update Temp_hasil2 Set KdPT = A.PTCD,
KdLjr = A.LKRJACD
>From (Select A38.NIK,A01.ptcd,A38.Lkrjacd
From AM382 A38
inner join
ap012 A01 on A38.nojob = A01.nojob
Where A38.tglavd =
(select max(B38.tglavd) from am382 B38
where A38.nik = B38.nik
and B38.tglavd <= Temp_hasil2.Tanggal)
And A01.tglavd =
(select max(B01.tglavd) from ap012 B01
where A01.nojob = B01.nojob
and B01.tglavd <= A38.tglavd)
)A
Where Temp_hasil2.NIK = A.NIK;

If I run this query at Postgresql 8.0.3 :
Error: ERROR: subquery in FROM may
not refer to other relations of same query level.

Can someone help me solve this?,
because I've a plan to migrate database
from postgresql 7.3.3 to postgresql 8.0.3,
and I have a lot of case like one above
at my postgresql 7.3.3 databases.

Thanks,
Louise Catherine
NB: Sorry for my poor English

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