Creating a Read Only profile in 8.4

I am new at the Postgres DBA – Admin stuff.   So when asked to create a read only profile for our database in Postgres 8.4 I did the following:

·         create role RO_User password 'xxxxxxxxxxx' NOSUPERUSER NOCREATEDB NOCREATEROLE INHERIT LOGIN;

·         select 'grant select on ' || tablename || ' to \"RO_User\"; 'from pg_tables where schemaname = 'public';

The commands worked fine.  But when I connected as RO_User and did a select against a simple table in the DB, I got access denied on the table.  

Can anyone point to my error?

Greg Della-Croce