si mal no recuerdo hay versiones de MySql que debes poner los goup a tu izquierda y tus acumulados a la derecha
Cita: SELECT source , count(vob_id) as total
FROM vob
GROUP BY source
ORDER BY count(vob_id) DESC
o cambiando la sentencia Order by
Cita: SELECT source , count(vob_id) as total
FROM vob
GROUP BY source
ORDER BY total DESC