Set up perfcalc

Hello.

I want to use the perfcalc extension to calculate total number of RDS Licenses from different servers.
Where do I start? When I create a rule at Setup - Agents - Calculate on the performance data of other checks I get an Internal error Exception NotImplementedError ()
Under Setup - Services - Enforced services - Calculated Performance Data Levels I can create a rule but it always stays at stale.
I already updated to 2.1.0p13

What is the method to do it? I would think the service is attatched to the Checkmk host and just sums the licenses to a new service.
Or is it possible to get notifications from a graph? I created a custom graph but I didn’t find an option to set values for warn/crit

Please help… Thank you

perfcalc is not documented as it could be

If you want commercial support for that extension please email to support@heinlein-support.de.