当FQL使用uid条件查询event_member表时获取Empty数组

Question

当我执行以下FQL查询时

SELECT uid, rsvp_status FROM event_member WHERE uid = me()

我得到了一份我参加的活动清单。当我执行以下任何一个FQL查询时

SELECT uid, rsvp_status FROM event_member WHERE uid = "{my uid written out}"
SELECT uid, rsvp_status FROM event_member WHERE uid IN ("{my uid written out}")

我得到以下空对象

{"data": []}

我想查询我的朋友公共活动。当我尝试使用以下任一查询

时

SELECT uid, rsvp_status FROM event_member WHERE uid = "{my friends uid written out}"
SELECT uid, rsvp_status FROM event_member WHERE uid IN ("{my friends uid written out}")

我再次获得以下空对象

{"data": []}

有什么建议吗？