I meant startDate and endDate which you used for calendar,
=Sum(if(date>=vStartDate and date <=vEndDate,amount_pg))
//date - your database date
//vStartDate and vEndDate are variables which you have used in calendars

As Vitalii suggested, you can also use set analysis for that,
=sum({<Date = {">=$(vStartDate )<=$(vEndDate)"}>}amount_pg)