Deferred Constraints Issues

Hi List;

I've placed this sql in a script:

psql my_db <<!
begin;
SET CONSTRAINTS ALL DEFERRED ;
delete from account where 1 = 1;
delete from cust where 1 = 1;
delete from cust_type where 1 = 1;
delete from cust_orders where 1 = 1;
commit;
!

The tables have relationships, however I expect the 'SET CONSTRAINTS
ALL DEFERRED' to defer constraint checks. When I run the script I get
this:

BEGIN
SET CONSTRAINTS
ERROR: update or delete on table "account" violates foreign key
constraint "account_rel" on table "cust_type"
DETAIL: Key (account_id)=(1) is still referenced from table
"cust_type".
ERROR: current transaction is aborted, commands ignored until end of
transaction block
ERROR: current transaction is aborted, commands ignored until end of
transaction block
ERROR: current transaction is aborted, commands ignored until end of
transaction block
ROLLBACK

Am I doing something wrong ? Or, is the 'SET CONSTRAINTS ALL DEFERRED'
not working properly ?

Thanks in advance...