Rolling 12 Month in a Graph / Diagram

[#1]

Hi,

I'm a qlikview newbie and just can't figure out if there's a way to display the cumulative sales of the last 12 Months for each month of the last year in a Graph.

I use calculating the twelve months' total

rangesum(above(total sum( Sales),0,12))

which appears to work fine.

Limiting the dimension to the previous year by

= if(Date>=AddMonths(MonthStart(today()),-12),month(Date) & year(Date))

seems to cut off the data previous to the first month, so I just get the proper result for the last month (though there is data in the data set going back to 2008):

Is there any way to include the data in the calculation of the sum though its date lies prior to the first date of the dimension?

Thanks for your help

Stefan