INHERIT and FOREIGN KEY issues

BEGIN;

CREATE TABLE A

(

idA serial not null primary key,

someColumn text

);

CREATE TABLE B

(

someData text

) INHERITS(A);

CREATE TABLE C

(

idC serial not null primary key,

anotherColumn text

);

CREATE TABLE BC(

idB int4,

idC int4,

 FOREIGN KEY (idB) REFERENCES B(idA),

 FOREIGN KEY (idC) REFERENCES C(idC)

);

COMMIT;

ERROR:  there is no unique constraint matching given keys for referenced table "b"

My question is: Shouldn't it get Table A primary key and create the foreign key?

Thx

Luiz Eduardo