How to filter data in list box level

[#1]

Hi..     

I have a calendar month from Jan to Dec (PFA) ... and i am using one button to select last 3 months of data ..for that using ACTION-->SELECT IN FIELD-->SEARCH STRING(='>='&MonthEnd(max({1} Day), -2)), but it is showing May, Jun, July data but i need to disply Apr,May and June data only ..i tried in many ways ..but not getting please any one can help  to get this..

Regards,

[#2]

try this

sum({<Date={">=$(=AddMonths(makedate(max(year),max(month),-3))"},year=,Month=>}Sales)

[er_mohit]

try this

='>='&MonthStart(max(CalendarDate),-3)&'<='&MonthEnd(max(CalendarDate),-1)

Replace with your Date Field

hope it helps