sto uscendo di testa cercando di capire dov'è l'errore di sintassi (riga 7: ON p.userid = c.user_id )
codice:
SELECT pts.userid, pts.points, com.value

  FROM (SELECT c.value, MAX(p.points) AS max_pts
        FROM  k6l0c_community_fields_values AS c
	WHERE c.value=16
         INNER JOIN  k6l0c_alpha_userpoints AS p             
         	ON p.userid = c.user_id   
	INNER JOIN  k6l0c_user_usergroup_map AS grp
		ON c.user_id = grp.user_id	
				WHERE   grp.group_id = 2
         GROUP BY c.value ) AS sub
INNER
  JOIN  k6l0c_community_fields_values AS com  
    ON com.value = sub.value     
INNER
  JOIN  k6l0c_alpha_userpoints AS pts
    ON pts.points = sub.max_pts
   AND pts.userid = com.id
INNER
  JOIN  k6l0c_users AS usr
    ON usr.id = pts.userid  


WHERE com.value!='' AND
       pts.points >0
	
ORDER BY pts.points DESC