Hi Madis,
Again thanks for giving me some direction. 
I have already created an Entity for Elimination Purpose and the number is calculated correctly. Just, I wondered why the number under this Elimination Entity is not aggregated to CSO member.
For your information, I guess the problem is coming from Audit Trail dimension.
In my testing, if I put in some number under "Input" in that Elimination Entity, it can be aggregated to CSO but not "IC Elim".
Any hints?
Antony