PL/pgSQL question

Hi All!
I'm trying to get working the below PL/pgSQL function without sucess.
The function is correctly created, but when I tested it i got:

# SELECT grantAccess('sara', 'sarapass');
ERROR: set-valued function called in context that cannot accept a set
CONTEXT: PL/pgSQL function "grantaccess" line 10 at return next
veillewm=#

What I'm missing?
Thank in advance
Younes

----------------- CODE BEGIN --------------------------
CREATE FUNCTION grantAccess(text,text) RETURNS SETOF users AS '
DECLARE
userlogin ALIAS FOR $1;
userpasswd ALIAS FOR $2;
row users%ROWTYPE;
BEGIN

FOR row IN SELECT user_id FROM users WHERE user_login = userlogin
AND user_passwd = userpasswd AND user_account = TRUE LOOP
RETURN NEXT row;
END LOOP;
RETURN;
END;
' LANGUAGE 'plpgsql';

----------------- CODE END --------------------------