MySQL - ORDER BY THEN不工作

Question

这个mySQL查询似乎是通过recCorrelation.correlation排序，而不是recCorrelation.following。语法有问题吗？

SELECT  recUser.userID, 
        recUser.email, 
        recUser.name, 
        recUser.surname, 
        recCorrelation.following, 
        recCorrelation.correlation
FROM    recUser, recCorrelation
WHERE   recUser.userID=recCorrelation.user1
GROUP   BY recUser.userID
ORDER   BY recCorrelation.following DESC, 
           recCorrelation.correlation DESC
LIMIT 50