unexpected output of rule

Platform used : Redhat Linux 7.2 kernel 2.4.20-28.7
Version Postgresql: postgresql-7.3.4-2PGDG

Problem:

--The following rule was created:--

create rule tbl_notities_project_id as
on insert to tbl_project_1
do
insert into tbl_notities (project_id) values (new.project_id);

--tbl_project_1 is the following table--

Column | Type | Modifiers

----------------------+----------------+----------------------------------------

project_id | integer | not null default
nextval('tbl_project_1
_project_id_seq'::text)
projectnaam | character(50) |
zoeknaam | character(12) |
projectomschrijving | character(50) |
adres_project | character(40) |
postcode_project | character(7) |
plaatsnaam | character(50) |
datum_invoer_project | date |
relatie_id | integer |
memo_bak | character(254) |
projectnummer_klant | character(32) |
projectstatus | character(8) |
memo | text |
bvo | real |
Indexes: tbl_project_1_pkey primary key btree (project_id)
Rules: tbl_notities_project_id

--tbl_notities is the following table--

Column | Type |
Modifiers
------------+--------------------------+---------------------------------------------------------------
notitie_id | integer | not null default
nextval('tbl_notities_notitie_id_seq'::text)
project_id | bigint |
datum | timestamp with time zone |
notitie | text |
Indexes: tbl_notities_pkey primary key btree (notitie_id)
Rules: wijzig_notitie

When a new record is inserted in tbl_project_1, the value of project_id in
tbl_notities is raised by 1.
The expected value "389" appeared in tbl_notities as "390". It seemed as if
"tbl_project_1_project_id_seq" was used in the created rule for the value
of "new.project_id".

The suspected behavior was confirmed when a new record in tbl_project_1 was
inserted. The new project_id was 391 instead of the expected 390.

Yours Sincerely,

Jaap Remerie

Remerie Bouw
Da Costastraat 111 huis
1053 ZJ AMSTERDAM
T. 020-6125072
F. 020-6125119
http://www.remerie.com