BPC Logic Issue

Hi,

I am trying to learn the script logic and facing this issue :

I want to calculate : ACCOUNT A = ACCOUNT B + ACCOUNT C.

FOR THIS I HAVE DEFINED THE SCRIPT LIKE THIS :

*XDIM_MEMBERSET CATEGORY = BUDGET

*XDIM_MEMBERSET TIME = %TIME_SET%

*WHEN ACCOUNT

*IS "B"

*REC(EXPRESSION = (%VALUE%)+[ACCOUNT].[C],ACCOUNT = "A")

*ENDWHEN

The code is getting validated successfully and when I am running it then following are the cases which I am getting :

In Excel Input Form if I enter : ACCOUNT B = 10 , ACCOUNT C = 10 THEN THE ACCOUNT A = 20 , which is correct and its working.

But when I enter the data in such way : ACCOUNT B =  ,ACCOUNT C = 10 ,ACCOUNT A = 0. It should show 10  but its not because I kept Account B blank this time.

So, my query is if above way is not correct then Please guide me how I can script : ACCOUNT A = ACCOUNT B + ACCOUNT C , so that it shows result in all condition even when any of the member account is blank .

Please guide.

Thanks

NATASHA