Tested Aqua Data Studio Aqua Data Studio 14.0.0-rc-13 Build #: 33892 on Ubuntu 12.04( Mongo DB 2.4.3)
drop collection orddate
go
insert into orddate(dates,funds) values(isoDate('2012-12-12T19:18:12.977Z'),10)
go
insert into orddate(dates,funds) values(isoDate('2012-12-13T19:18:12.977Z'),11)
go
insert into orddate(dates,funds) values(isoDate('2012-10-14T19:18:12.977Z'),1)
go
insert into orddate(dates,funds) values(isoDate('2012-10-2T19:18:12.977Z'),5)
go
select dates,month(dates) from orddate group by dates
--Exception occurred during aggregation: exception: can't convert from BSON type EO0 E00 EOO to Date
go
select month(dates) from orddate
--works correct
go
select * from orddate
go