ORA-06512: in "SYS.DBMS_SQL"

Hello,Database Oracle 11.2

I have this procedure:
but I when I execute it show this errors:

ORA-01031: privilegios insuficientes

ORA-06512: en línea 3

ORA-06512: en "SYS.DBMS_SQL", línea 1575

ORA-06512: en "PRUEBA", línea 37

ORA-06512: en línea 6

I GRANT IT PRIVILEGES:

grant execute on sys.DBMS_SQL to user;

but this error continue.



BEGIN
EXECUTE immediate 'delete
from   au_consult_field cca
where
  cca.consult_id in
    (select
       con.consult_id
     from
       au_consult con
     where
       con.table_id = 12345) ';

EXECUTE immediate 'delete
from
  au_consult con
where
  con.table_id = 12345 ';

EXECUTE immediate 'create or replace trigger AUDIT_TABLA