finding UNIQUES in information_schema

Hi all. Im failing while trying to obtain some metainfo from
information_schema. Acording to the docs, constraint_column_usage and
key_column_usage views contains some information about constraints and
indexes.

See:                      Table "public.almatnov"  Column    |          Type          |           Modifiers
-------------+------------------------+--------------------------------formu       | integer                |alucod
| integer                | default 0codcarr     | character varying(3)   | default ''::character varyinganifm       |
charactervarying(2)   | default 20comentarios | text                   | default ''::text
 
Indexes:   "almatnov_alucod_codcarr_idx" UNIQUE, btree (alucod, codcarr)   "almatnov_codcarr_alucod" UNIQUE, btree
(alucod,codcarr)
 



And now:
ematerias=# SELECT * from information_schema.constraint_table_usage
where table_name='almatnov';table_catalog | table_schema | table_name | constraint_catalog |
constraint_schema | constraint_name
---------------+--------------+------------+--------------------+-------------------+-----------------
(0 rows)

ematerias=# SELECT * from information_schema.key_column_usage where
table_name='almatnov';constraint_catalog | constraint_schema | constraint_name |
table_catalog | table_schema | table_name | column_name |
ordinal_position | position_in_unique_constraint

--------------------+-------------------+-----------------+---------------+--------------+------------+-------------+------------------+-------------------------------
(0 rows)

1) Im a doing anything wrong?
2) It is safe to extract metainfo from pg_catalog?

Thanks!

Gerardo