problem with pl/pgsql

I'm trying to build a table function using pl/pgsql. I've done this
successfully many times in the past, but this is the first time I've tried
to build up and execute a dynamic query, and either it or I (probably I)
am getting confused.

The error I get is:
foo=# select * from fetch_artistset_by_artists('{1}');
WARNING:  Error occurred while executing PL/pgSQL functionfetch_artistset_by_artists
WARNING:  line 30 at return next
ERROR:  Attribute "r" not found

The stored proc is:
CREATE or REPLACE FUNCTION Fetch_ArtistSet_By_Artists(integer[]) RETURNS setof integer AS
'DECLARE
        artists alias for $1;
        index   integer := 1;
        total   integer := 0;
        r       record;
        q       text := ''select setID from (select setID,count(*) as c from artistSet where'';
    BEGIN
        WHILE artists[index] > 0
        LOOP
            if index > 1
            then
                q := q || '' or'';
            end if;

            q := q || '' artistID = '' || artists[index];

            total := total + 1;
            index := index + 1;
        END LOOP;

        if total = 0
        then
            RETURN;
        end if;

        q := q || '' group by setID) as foo where c = '' || total;

        for r in execute q
        LOOP
            RETURN next r;
        END LOOP;
        RETURN;
    END;
' LANGUAGE 'plpgsql';

The schema is:
create table artistSet
(
    memberState integer not null,
    setID integer not null references artistSetInfo(id),
    artistID integer not null references artist(id),

    primary key (setID, artistID)
);

Any thoughts? The error is on the "RETURN next r;" line, which has worked
fine for me in the past, unless I'm making a typo I'm just not seeing. So
that leads me to believe it has something to do with the dynamic query,
but I don't know what it would be.....