Any hints on why key figure in BW is different from its equivalent in R3?

Question

Hello,
In a BW report, I tracked down a key figure which was 3000. I verified it through the tcode listcube and for the same selection criteria found the number to be 3000. The problem is that the user expected it to be 1000.
Through the transfer structure, I found out that this key figure does not come directly from R3 but rather, it is a zzkeyfigure, being populated through a program.
In CMOD (R3), I identified that zzkeyfigure was sourced from kwmeng (from the table vbap). In R3, with se16n on the table vbap with the right selection criteria, I identified kwmeng also as 1000.
Can you help me figure out why this figure (1000) in R3 is turning up in the BW backend objects as 3000?
Additional Info: the code in CMOD
select  single kwmeng vrkme
       into  (W_MC12VC0ITM-zzkeyfigure1,
              W_MC12VC0ITM-zzkeyfigure2)
       from vbap
       where vbeln = W_MC12VC0ITM-vgbel
         and posnr = W_MC12VC0ITM-vgpos.

Answer 1

Hi Ken,
I am the one who is to defnitely advise the users as to what the cause of this proble is about but I could hardly comprehend the hints you dropped.
From the above message, how did you deduce that my data sourse is delta and produces reversals when documents change (for loading direct to a cube)?
You noted that if that is the case then "the look up value will also need to be reversed" I did not understand this. Can you explain what you meant by that?
Although I did not understand this comment you made:
" ... If you maintain your datasource in RSA6 you will find an inversion setting (next to hide field) which I believe will reverse your custom keyfigure when the record is a reversal.. "
I went into rsa6 (in R3) and ...double clicked on 2LIS_12_VCITM to see the area with the inversion column. None of the fields with checked boxes was of interest to my reseach. i.e none of the keyfigures in question was checked . Can you explain this quote and let me know what I was to expect in this this area?
Also you implied that in R3, one can decide to maintain datasource in Rsa6 or rsa3? Did I get you right? what are all the options that you can maintain daaourse in and if so, under what circumnstances do you choose one over the other?
Thanks.