I used the following formula:

SUM(COALESCE(PU_SUM("EKPO","EKBE"."MENGE"*("EKPO"."UMREZ"/"EKPO"."UMREN"),"EKBE"."VGABE" IN ('1','7') AND "EKBE"."BEWTP" IN ('E','O') and "EKBE"."SHKZG" = 'S'),0) -

COALESCE(PU_SUM("EKPO","EKBE"."MENGE"*("EKPO"."UMREZ"/"EKPO"."UMREN"),"EKBE"."VGABE" IN ('1','7') AND "EKBE"."BEWTP" IN ('E','O') and "EKBE"."SHKZG" = 'H'),0))

The KPI is aggregated at a material level and hence a CASE WHEN statement is giving me a warning. I had to use COALESCE becuase null value in the second part of the formular is making the entire value as NULL. Does this formula create rounding errors or with the existence of 29-Feb in the data? If I select March 2 - March 31, the result is accurate. Any ideas?