Facebook已经确认这是一个错误：
http://developers.facebook.com/bugs/292220680814266

Facebook has confirmed this as a bug: http://developers.facebook.com/bugs/292220680814266

1个月，仍然没有修复...

1 month and still no fix ...

@Mod：同样的问题稍后在这里被问到： Facebook图形API搜索通过电子邮件突然停止工作

@Mod: the same question was asked later here: Facebook Graph API "search" by email suddenly stopped working