Query Problem!! - Mailing list pgsql-bugs

I have PostgreSQL v7.02 in RedHat 6.2;

I have problem with is Query:
select name, 'user' as class from smuser union select name, 'group' as clas=
s from smgroup order by class;

sentence problem is:{ order by class} !!!!=20

thank you,=20
Christian Gonzalez