What I thought was going to be a nice and easy calculation has turned into my biggest headache. I have two tables in the same database. One has the number of installed units, the other has the number of customer calls. What I want to do is divide the number of calls per month by the running sum of the number of installs by product group. I have tried joining and blending by product group and date. Neither seems to give me what I want. The calculation I am using is COUNTD(Cases.ServiceRequests)/RUNNINGSUM(COUNTD(Installs.SerialNumber)). The calculation itself is valid but the output is incorrect. Has anyone tried to do something similar and been successful?