SQL & PL/SQL

Hi,
I have a package that works with my user but when I try grant execute on this package I get

  
declare
      v_id number;
     begin
          v_id := liste_pkg_lista.liste_lista_func(9);
        dbms_output.put_line(v_id);
end;
SQL> /
9

PL/SQL procedure successfully completed.

SQL> grant execute on liste_pkg_lista.liste_lista_func to public;
grant execute on liste_pkg_lista.liste_lista_func to public
                                 *
ERROR at line 1:
ORA-04042: procedure, function, package, or package body does not exist

can you tell me how to grant execute on it to public?

Thank you