See my old, but detailed post on proper universe measures here, please: diff between Select SUM (Table. Field) & Select Table. F
Should you be accessing an SAP BEx query then:
a) Make sure you are using direct access from Webi to SAP BEx query (via BICS, meaning: NO old fashioned OLAP universe!)
b) Ensure your SAP BI BusOjects platform, installed SAP GUI/SAP DLLs and SAP BW are on a recent patch level such as: SAP BI BusObjects 4 SP6 with Patch 3, SAP GUI 730, and SAP BW 7.3 SPS9 I believe.
Andreas 
(BOB member since 2002-06-20)