Function Issue and casting

Hi friends, It's my first time I'm writing to the list. All days I enjoy the
list!
I declare a function, and when I want to call this, it fails.

My function:
CREATE OR REPLACE FUNCTION
alta_docente(integer,varchar,varchar,varchar,bigint,varchar,integer)
RETURNS VOID AS
$body$
declare
codigo integer;
begin
INSERT INTO persona(cod,dni,nombre,apellido,domicilio,telefono) VALUES
(DEFAULT,$1,$2,$3,$4,$5);
codigo := currval('persona_cod_seq');

INSERT INTO persona_docente(cod,legajo,antiguedad) VALUES
(codigo,$6,$7);
end;
$body$
LANGUAGE 'plpgsql';

The call I'm doing:
SELECT alta_docente(2323232,cast('Mariela' AS varchar),cast('Botti' AS
varchar),cast('232 de Noviemb23' AS varchar),cast(2312312321AS
bigint),cast('323232A' AS varchar),23)

And here is the error:

ERROR: function alta_docente(integer, character varying, character varying,
character varying, bigint, character varying, integer) does not exist at
character 8
HINT: No function matches the given name and argument types. You might need
to add explicit type casts.
STATEMENT: SELECT alta_docente(2323232,cast('Mariela' AS
varchar),cast('Botti' AS varchar),cast('232 de Noviemb23' AS
varchar),cast(2312312321AS bigint),cast('323232A' AS varchar),23)

I don't know what's the problem, because I did all the explicit cast I think
to convert types. If someone can help me, It would be great!

Thanks a lot

JP Cook

Sorry about my bad english!