You can create a calculated column which shows the difference and then use measure names and measure values to create stacked bar chart.
Check out the below link for explanation :
thank you very much for your suggestion.
Unfortunately, it doesn't exactly fit my purpose (should've described it more specified).
So here is what I need to do in detail:
I have an actual value for May and a forecast value for June.
Then I am trying to show what the difference between the two values is in a stacked bar.
But I want to do this for multiple KPIs in the same graph.
Therefore, I can't use the time on columns because I have the different KPIs that would be mixed.
But I also cant' use the KPIs on the columns because then I can't create a stacked bar.
To solve your requierment, you may have to play with table index.
1. put your date filed in the viz, year, month in discrete for instance
2. create a calculated field with this template: LOOKUP(SUM( [Forecast]) , 1) , call it "Forecast Month +1"
3. do a combo chart with sum(actual) and "Forecast Month +1"
4. you can also create the calculation of the difference and put it in Label.