Build Routine-Account releted to inputted Customer

Hi all,
I need to write build routine regard to the account, from account application i need to get the inputted customer id from that customer i need to select the primary account related to that customer.
for this may i use the customer.account...
please any one may reply for this quiry.
My prog:
INIT:
DEBUG
FN.ACC='F.ACCOUNT' ; F.ACC=''
Y.APP='ACCOUNT'
Y.APP.FLD='LR.PRIM.ACC'
Y.APP.POS=''
Y.ACC.ID=ID.OLD
RETURN
OPENFILE:
CALL OPF(FN.ACC,F.ACC)
CALL GET.LOC.REF(Y.APP,Y.APP.FLD,Y.APP.POS)
Y.PRM.ACC=Y.APP.POS
RETURN
PROCESS:
LOCATE 'CUSTOMER' IN ENQ.DATA<2,1> SETTING Y.CUS.POS ELSE NULL
Y.CUS.ID=ENQ.DATA<4,Y.CUS.POS>
CALL F.READ(FN.ACC,Y.ACC.ID,R.ACC,F.ACC,ACC.ERR)
Y.CUS=R.ACC<AC.CUSTOMER>
Y.PR.STATUS=R.ACC<AC.LOCAL.REF,Y.PRM.ACC>
Y.FIELDS.COUNT=DCOUNT(ENQ.DATA<2>,VM)+1
ENQ.DATA<2,Y.FIELDS.COUNT>='CUSTOMER'
ENQ.DATA<3,Y.FIELDS.COUNT>='EQ'
IF Y.PR.STATUS EQ "YES" THEN
ENQ.DATA<4,Y.FIELDS.COUNT>=Y.CUS
END
RETURN
END

its not working properly,if anything make changes in this..