subquery in FROM must have an alias

Hi all,

This has been asked before and answered as well.
http://archives.postgresql.org/pgsql-sql/2007-12/msg00002.php but I
still cant figure out why postgres throws this error message even when
I have provided the aliases. My query:

select a,b
from (billing.item JOIN (
select *
from ( billing.invoice JOIN billing.customer
on (id_customer_shipped = customer_uid and
address = 'pgh' ))
as temp2 ))
as temp;

I have two from clauses so I have provided two corresponding alias
names for those two from clauses. But, still I get the error message

ERROR: subquery in FROM must have an alias
HINT: For example, FROM (SELECT ...) [AS] foo.

Any help on this will be greatly appreciated. I am using version 8.3.3
running on ubuntu.

Thanks,
Ashutosh