Compare Month vs Previous including Month in dimension

[#1]

Hello,

i'm trying to compare month vs previous month with a simple control.

-- Intérêts compris -- Période NROTIT PM NETTE en parts Mvts en parts Frais S/E en parts Contrôle Total 47124,751108 23446,261316 -64,615371 -23743,105163 11-2009 19712 0,000000 -38,482464 -11,880941 -50,363405 10-2009 19712 23432,009350 -232,071860 -28,660548 -23692,741758 09-2009 19712 23692,741758 23716,815640 -24,073882 -0,000000

I have a stock at the end of a month (PM Nette en parts) and movements during a month.

I need to control if (PM NETTE en parts 09-2009)+(Mvts en parts 10-2009)+(Frais S/E en parts)-(PM NETTE en parts 10-2009) = 0

Période is a calculated dimension: =timestamp(monthname(DATE_VALEUR),'MM-YYYY')

I have try with this, but does'nt work.

=sum(if (InMonthToDate (DATE_VALEUR, DATE_VALEUR, -1), PM_PARTS_NET))

+ column(2)+column(3)

-sum(if (InMonthToDate (DATE_VALEUR, DATE_VALEUR, 0), PM_PARTS_NET))

Can someone help me?

Thanks

Laurent