Trigger from a function

Hello all,

I have a problem with a trigger which is executed when i make an UPDATE trought a simple query, but
not when the UPDATE is made in a store procedure.

Maybe i'm missing something in the declaration of the function and i would appreciate any help.
T
his is the function:

CREATE OR REPLACE FUNCTION X
RETURNS SETOF void AS
$BODY$

begin
update A;
end;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;

The trigger:

CREATE TRIGGER Y
BEFORE INSERT OR UPDATE
ON A
FOR EACH ROW
EXECUTE PROCEDURE Z;

CREATE OR REPLACE FUNCTION Z
RETURNS "trigger" AS
$BODY$
begin
if (tg_op in ('INSERT', 'UPDATE', 'DELETE')) then
update A;
end if;
$BODY$
LANGUAGE 'plpgsql' VOLATILE;

Thanks in advance.
Danilo Guevara
Departamento de Sistemas
Acceso Crediticio SAC