Set expression for dates of a month from previous year

[#1]

Hi,

I
need to create a calculated dimension to get dates of a month from
previous year. I will be using this as oppose to current date (
4/5/2014):

Date(of a month from last year)	Total Sales
4/1/2013	100252.00
.
.
4/30/2013	90548.00

To note - I have date two variables to get the start date of a month and end date of a month from last year.

Need help with suggestion on how this can be done with set expression.

[Gysbert_Wassenaar]

Don't use a calculated dimension. Just use your date field as dimension and a set analysis expression that limits the records to those of the requested period: sum({<Date={">=$(vStartDate)<=$(vEndDate)"}>}Sales).

[#3]

Thanks, Gysbert - this was helpful; appreciate your suggestion.