Error Returned by A Function

Hi all, I have a short function below that is return me an error, and I
can't figure out what I should do to fix it. Can anyone help? Archives have
not helped. The error I get is:

select * from current_neighbors(2);

ERROR: cannot assign non-composite value to a row variable
CONTEXT: PL/pgSQL function "current_neighbors" line 15 at assignment
------------------

CREATE TYPE typ_remote_net AS
(remote_net varchar);

CREATE OR REPLACE FUNCTION current_neighbors(integer)
RETURNS SETOF typ_remote_net AS
$BODY$

DECLARE

work_if_id ALIAS FOR $1;

first_record char(1);
last_remote varchar;
last_neighbor_state integer;
output_count integer := 0;
returnValue typ_remote_net;
workarea adns_neighbor_history%ROWTYPE;

BEGIN

returnValue := 'none';
first_record := 'Y';
FOR workarea IN
select if_id, updated_time, remote_net, neighbor_state,
last_checked
from adns_neighbor_history
where if_id = work_if_id
order by BY 1,3,2
loop
if first_record = 'N' then
if workarea.remote_net = last_remote then
if workarea.neighbor_state = last_neighborstate then
-- same values, no action required
NULL;
else
-- store latest neighbor state
last_neighbor_state := workarea.neighbor_state;
end if;
else
-- see if last remote needs to be reported
if last_neighborstate > 0 then
returnValue = last_remote;
RETURN NEXT returnValue;
output_count := output_count + 1;
end if;
last_remote := workarea.remote_net;
last_neighbor_state := workarea.neighbor_state;
end if;
else
first_record = 'N';
last_remote := workarea.remote_net;
last_neighbor_state := workarea.neighbor_state;
end if;
end loop;

if (last_neighbor_state > 0) then
RETURN NEXT returnValue;
else
if output_count = 0 then
returnValue := 'none';
RETURN NEXT returnValue;
end if;
end if;

RETURN;
END
$BODY$
LANGUAGE 'plpgsql' VOLATILE;