Set Analysis - Previous Month Values in Pivot Table

[#1]

Hi,

I seem to have a problem, i've tried searching the forum and applying previous answers to my problem, but I cannot somehow get any of them to work correctly. I am trying to display the Sum Dollar Total of the

I have a variable SelDate which is a user chosen date with the property 'Always One Selected Value'.

I calculate SelDate at the time of script loading deriving it from ToDate:

FormattedDate:
LOAD ToDate,
Date(MonthStart(ToDate), 'MMM YYYY') as SelDate
RESIDENT DataSet;

This sets every item in the dataset to have a date of the 1st of the respective month and year, eg. 01/01/2009, 01/04/2009.

In my pivot table I am trying to use an expression like this, however it does not appear to work:

Sum({1<SelDate={$(=(AddMonths(SelDate,-1)))}>} DollarAmount)

It just returns dashes, any ideas as to what I'm doing wrong?

Thanks in advance

Michael

[#2]

could you upload a QVW with an example of your information?

[#3]

try

Sum({1<SelDate={"$(=(AddMonths(SelDate,-1)))"}>} DollarAmount)