Get cumulative total of month before min selected months

[BobKoenen]

Hi All

I am creating a Matrix where in the first column the value of a measure needs to show the cumulative total of all months before the minimal selected month. I could select multiple following months
So if I would select Jan, Feb, March. This column would give me the **bleep** total from December
For April May June this column would give me the **bleep** total from March

I have a created cumulative total measure

Voorz **bleep** =

CALCULATE( [Mutatie voorziening];

    FILTER( ALL ('Calendar');

'Calendar'[Date] <= MAX('Calendar'[Date] )))

And a measure which gives me the cumulatieve total upon last month. 
voorziening **bleep** begin periode = CALCULATE([Voorz **bleep**];DATEADD('Calendar'[Date];-1;MONTH))

This works fine if I only select one month in the date slycer. But if I would select multiple months it goes bananas. 

I think it is because it takes the -1 from the max month. And I would like to take the -1 from the min month selected. 

can you Help me?

[Greg_Deckler]

Difficult to say, change your MAX to MIN?

Please see this post regarding How to Get Your Question Answered Quickly: https://community.powerbi.com/t5/Community-Blog/How-to-Get-Your-Question-Answered-Quickly/ba-p/38490