Table Inheritance and foreign key problem.

I make 3 tables with this senario:
b (id) extends a (id)
and
c (id) references a (id)

i insert one record to  table b (id = 1)
and then i try to insert a record in table C  (id = 1)
but it is not possible, i get error
(look at the sql statements above)


NOTE
if the C (id) references the b (id) the insert in  table C
is possible.

I try this to postgresql 8.1.2 and 8.1.4


above is the exact SQL STATMENTS:

============================================

DROP TABLE a;
DROP TABLE b;
DROP TABLE c;

CREATE TABLE  a (id integer primary key);

CREATE TABLE  b (id integer primary key) INHERITS (a);

CREATE TABLE c (id integer primary key references a(id));

insert into b values (1);





SELECT * from b;
 id
----
  1
(1 row)


SELECT * from a;
 id
----
  1
(1 row)


INSERT INTO c VALUES (1);
ERROR:  insert or update on table "c" violates foreign key constraint
"c_id_fkey"
DETAIL:  Key (id)=(1) is not present in table "a".



============================================


Thanks

Kostas Maistrelis.