ASP Page retrieve Data from Advantage Database

[Atheneos]

Hello,
I've trying since a few Days to find a Solution for the following Problem:
(complete Query below)

My Query works if I put FROM Fpolicy WHERE Customer =12345
instead of
FROM Fpolicy WHERE Customer =?
I tried it with
FROM Fpolicy WHERE (Customer =::Customer::)
No Success
FROM Fpolicy
Brings all Datasets in Fpolicy

Did anybody see some errors in the SQL Query?
Any suggestions?

I ask it in this Forum because I want to post the Number for "Customer=?" via a asp Page someting like:

http://test/test.asp?Customer=12345

 
FPOLICY.CUSTOMER,
FPOLICY.AGREEMENT,
FPOLICY.CHARACTERISTIC,
FPOLICY.MASTERPOLICY,
FPOLICY.POLICY,FPOLICY.EFFECTIVEDATE,FPOLICY.EXPDATE,
FPOLICY.POLICYCODE,
FPOLICY.GROSSPREMIUM,
FPOLICY.BRANCH,
FPOLICY.INSCO AS COMPANY,
FPOLICY.CATEGORY,FPOLICY.RENEWIT,
FPOLICY.CANCELDATE,FPOLICY.TRANSACTIONCODE,
 
( SELECT FAGETR.AMOUNT- Round(ISNULL(Sum(FAGESTL.AMOUNT),0),2)
  FROM  FAGETR LEFT JOIN FAGESTL ON FAGETR.CODE = FAGESTL.TransactionClosed, FAGETRT
  WHERE FAGETR.TRANSACTIONTYPE=FAGETRT.CODE
  AND FAGETRT.IsSettled=True
  AND FAGETRT.SETTLEMODULE = 'GRE'
  AND FAGETR.OWNER=1
  AND FAGETR.OWNERCODE=FPOLICY.TRANSACTIONCODE
  GROUP BY FAGETR.AMOUNT
 
UNION
 
  SELECT  FCUSTR.AMOUNT- Round(ISNULL(Sum(FCUSSTL.AMOUNT),0),2)
  FROM  FCUSTR LEFT JOIN FCUSSTL ON FCUSTR.CODE = FCUSSTL.TransactionClosed, FCUSTRT
  WHERE FCUSTR.TRANSACTIONTYPE=FCUSTRT.CODE
  AND FCUSTRT.IsSettled=True
  AND FCUSTR.OWNERCODE=FPOLICY.TRANSACTIONCODE
  AND FCUSTR.OWNER=1
  GROUP BY FCUSTR.AMOUNT) AS BALANCE
 
FROM Fpolicy WHERE Customer =?