set analysis - count when value is a given month

[Rkota]

HI there - would greatly appreciate any help with the error in the following expression

=Count({<MoveMonth ={">=$(=Date((AddMonths(Today(),-3)),'MMMMM')"}>} unittranid)

essentially, I'm trying to count by month I.E count(unittranid) when MoveMonth=August - as it is today

"Error in set modifier ad hoc element list; ',' or ')' expected.

Thanks

[its_anandrjs]

You can close another response as well as Correct or helpful.