KPI Matrix - Calc KPI Index issue

[FraNat]

In the example file of Power KPI Matrix it is possible to filter the visual by Country, but if I want to see, for instance, both France and Germany together then the KPI Indicator Status does not work anymore (it just sums the Calc KPI Index values instead of calculating them again). 
How can I solve this problem with this Custom Visual (I'm using the Row_Based_Metrics)? Is it possible to modify the Calc KPI Index formula so it calculates it again when I want to see the KPI for the whole company instead of only one country?
Thanks in advance for your support.