Privileges on sequences

Hello,
We are using PGSQL 8.3.4

I have problem to grant privileges to a sequence.
If I grant all to the user I can do something like :
SELECT nextval('reflex_cited_reports_id');
SELECT nextval('reflex_cited_reports_id');
 nextval
----------
 40442939
(1 row)


BUT if I grant the same priv to the group (that include the user) :

SELECT nextval('reflex_cited_reports_id');
ERROR:  permission denied for sequence reflex_cited_reports_id

some info :

canlii_integration_tests=# SELECT nextval('reflex_cited_reports_id');
 nextval
----------
 40442939
(1 row)

canlii_integration_tests=# SELECT * from pg_roles where
rolname='soft_reflex_externe';
       rolname       | rolsuper | rolinherit | rolcreaterole |
rolcreatedb | rolcatupdate | rolcanlogin | rolconnlimit | rolpassword |
rolvaliduntil | rolconfig |    oid

---------------------+----------+------------+---------------+-------------+--------------+-------------+--------------+-------------+---------------+-----------+-----------
 soft_reflex_externe | f        | f          | f             |
f           | f            | t           |           -1 | ********    |
infinity      |           | 820769731
(1 row)

canlii_integration_tests=# SELECT * from pg_group where
groname='reflex_lecteurs';
     groname     | grosysid |
grolist
-----------------+----------+-------------------------------------------------------------------
 reflex_lecteurs |    16431 |
{16400,16409,16417,16418,16424,16434,16479,16499,16500,820769731}
(1 row)



Is it a bug ? Or am i doing something wrong

Regards,