passing parameters in the routine

Thank you very much dear for the reply you gave me,it really helped me but now am getting the error bellow as i continue my development.
_BNK/SYSTEM.END.OF.DAY3_IC.COB_2_16 JUL 2013_08:55:15_SSELECT FBNK.TRANSACTION.s
_BNK/SYSTEM.END.OF.DAY3_IC.COB_2_16 JUL 2013_08:55:16_SSELECT FBNK.GENERAL.CHARs
_BNK/SYSTEM.END.OF.DAY3_IC.COB_2_16 JUL 2013_08:55:16_SELECT FBNK.ACCOUNT.COMPEs
Invalid or uninitialised variable -- NULL USED ,
Var (UNKNOWN) , Line 128 , Source CALC.IC.CHARGE
_BNK/SYSTEM.END.OF.DAY3_IC.COB_2_16 JUL 2013_08:55:19_Fatal error in CALC.IC.CH*
jsh live ~ -->


my new routine is as bellow

* <Rating>-34</Rating>
* BY OSBERT

*
SUBROUTINE NO.ACTIVITY(AC.NO,Y.FRM,Y.TO,BASE.AMT,BASE.CCY)

$INSERT I_COMMON
$INSERT I_EQUATE
$INSERT I_F.ACCOUNT
$INSERT I_F.COMPANY
$INSERT I_F.CUSTOMER
$INSERT I_ENQUIRY.COMMON
$INSERT I_F.ACCT.ACTIVITY
$INSERT I_F.FUNDS.TRANSFER
$INSERT I_F.CURRENCY
$INSERT I_F.MNEMONIC.COMPANY
$INSERT I_F.NUMBER.OF.CREDIT



GOSUB OPENFILE
GOSUB GET.AC
RETURN

OPENFILE:

FN.CURR = 'F.CURRENCY' ; F.CURR = ''
CALL OPF(FN.CURR,F.CURR)



FN.ACC = 'F.ACCOUNT'
F.ACC = ''


Y.TD.DATE = TODAY
Y.DATE = Y.TD.DATE
Y.YEAR = Y.DATE[1,4]
Y.MONTH = Y.DATE[5,2]
IF Y.MONTH = '01' THEN
Y.MONTH = '12'
Y.YEAR -= 1
END ELSE
Y.MONTH -= 1
Y.MONTH = FMT(Y.MONTH,"R%2")
END
IF Y.MONTH = '02' THEN
IF MOD(Y.YEAR,4) = 0 THEN
Y.END.DATE='29'
END ELSE
Y.END.DATE='28'
END
END ELSE
* A = INDEX('04 06 09 11',Y.MONTH,1)
IF INDEX('04 06 09 11',Y.MONTH,1) > 0 THEN
Y.END.DATE = '30'
END ELSE
Y.END.DATE = '31'
END
END

START.DATE=Y.YEAR:Y.MONTH:'01'
Y.DAY=Y.YEAR:Y.MONTH:Y.END.DATE



GET.AC:


FN.ACCT = 'F.ACCT.ACTIVITY'; F.ACCT = ''
CALL OPF(FN.ACCT,F.ACCT)

*FN.CAT = 'FBNK.NUMBER.OF.CREDIT' ; F.CAT = ''
*CALL OPF(FN.CAT,F.CAT)

FN.ACC = 'F.ACCOUNT'; F.ACC = ''
CALL OPF(FN.ACC,F.ACC)

CALL F.READ(FN.ACC,AC.NO,R.ACC.REC,F.ACC,E.ACC)
OPEN.DATE = R.ACC.REC<AC.OPENING.DATE>
* Get Account Activity Records
Y.DATE = Y.YEAR:Y.MONTH
Y.ACCT.ID = AC.NO:'-':Y.DATE
Y.ACTIVITY = '0.00'

CALL F.READ(FN.ACCT,Y.ACCT.ID,R.ACCT.REC,F.ACCT,E.ACCT)
Y.TRAN.CODE = R.ACCT.REC<IC.ACT.TRANSACT.CODE>
Y.CNT = DCOUNT(Y.TRAN.CODE, @VM)

FOR ZZ = 1 TO Y.CNT

Y.CODE = R.ACCT.REC<IC.ACT.TRANSACT.CODE,ZZ>
IF Y.CODE EQ '130' OR Y.CODE EQ '132' THEN
Y.ACTIVITY = '1'
END ELSE
Y.ACTIVITY = '0'
IF ZZ EQ Y.CNT THEN
BASE.AMT = '15000'
BASE.CCY =R.ACC.REC<AC.CURRENCY>

END
END

NEXT ZZ


* RETURN

*GET.AC1:

* CALL OPF(FN.ACC,F.ACC)
*CALL F.READ(FN.ACC,AC.NO,Y.REC,F.ACC,R.ERR1)
* BASE.AMT =R.ACC.REC<AC.OPEN.CLEARED.BAL>
*BASE.AMT = '15000'
*BASE.CCY =R.ACC.REC<AC.CURRENCY>

RETURN

END