sap bpc nw script logic for subtraction

[Riaz]

Hello Experts,

Need to calculate the difference between
a. Difference of Intercompany AR/AP, Intercompany loans to be stored in BPC_I1
b. Difference of Intercompany Inhouse clearing revaluations account, to be stored in BPC_I1

Below is the code written.

*SELECT(%TIME_PERIOD%,"[ID]",TIME,"OPEN = 'Y'")

*XDIM_MEMBERSET TIME = %TIME_PERIOD%
*XDIM_MEMBERSET AUDITTRAIL = ECC_GL,ECC_ELIM,IC_ELIM
*XDIM_MEMBERSET RPTCURRENCY = USD
*XDIM_MEMBERSET FLOW = BAS(Total_Flow)

*WHEN ACCOUNT
*IS BAS(25),BAS(26)
*REC(EXPRESSION=%VALUE%,AUDITTRAIL=BPC_I1)
*IS 13042000,13060010
*REC(EXPRESSION=%VALUE%,AUDITTRAIL=BPC_I2)
*ENDWHEN

*WHEN AUDITTRAIL

*IS BPC_I1, BPC_I2
*REC(EXPRESSION= %VALUE% AUDITTRAIL(BPC_IC) = AUDITTRAIL(BPC_I1) - AUDITTRAIL(BPC_I2)

*ENDWHEN

The above logic is giving an error.
Hope having help!  Thanks in advance.

Regards,
Usman