BPC 75NW YTD / Periodic Measure query

The Application is currently set to YTD. The Inputs are therefore done on YTD level for Costs. Headcount is a statistical account with AST account type, so YTD/Periodic measures become irrelevent.

Now, What I need is Periodic Costs Divided by HC to get Cost/HC (Cost_HC_Centre) and this is the script that I am running:

*SELECT (%BUS%, "[ID]", BUSAREA, "[CALCULATION]=Y")

*FOR %YEAR%=2011,2012

*FOR %MONTH%=JAN,FEB,MAR,APR,MAY,JUN,JUL

*FOR %BA%=%BUS%

*RUNALLOCATION

*FACTOR=1/USING

*DIM CATEGORY WHAT=ACTUAL; WHERE=<<<; USING=<<<

*DIM TIME WHAT=%YEAR%.%MONTH%; WHERE=<<<; USING=<<<

*DIM DATASRC WHAT=INPUT; WHERE=<<<; USING=<<<

*DIM FLOW WHAT=F_999; WHERE=<<<; USING=<<<

*DIM CURRENCY WHAT=INR; WHERE=<<<; USING=<<<

*DIM COSTCENTER WHAT=[BUSAREA]="ADM_%BA%"; WHERE=<<<; USING=NO_COSTCENTER

*DIM PROCESS WHAT=NO_IO; WHERE=<<<; USING=BAS(%BA%)

*DIM ACCOUNT WHAT=BAS(Salary_and_Benefits); WHERE=Cost_HC_Centre; USING=HC

*ENDALLOCATION

*COMMIT

*NEXT

*NEXT

*NEXT

By doing so, it is calculating it as YTD Cost / HC where I need Periodic Cost / HC

Please let me know how can I achieve the same.

Thanks.