Complex QUERY with Variables

Question

I created a complex query to extract data from Journal entry and from Journal voucher. I post here a simplified version where I have deleted UDO references.
I buit it in the Query analizer and it runs ok.
I copied in SAP and it runs ok too.
Now, I need to ask for the start date and end date, as in the first lines of script. But SAP raise an error message I dont understand. I tried to use '[%0]' and '[%1]' insthead of '2008/01/01' and '2008/02/29' 
DECLARE @D1 DATETIME
DECLARE @D2 DATETIME
SET @D1='2008/01/01'
SET @D2='2008/02/29'
SELECT * FROM
SELECT  
     A.ACCOUNT AS 'CO.GE ITALIA',
     OACT.ACCTNAME AS 'NOME CO.GE ITALIA',
     SUM(CASE WHEN (A.ACCOUNT>='500000' AND A.ACCOUNT<'600000' AND DEBIT<>0) THEN -DEBIT WHEN (A.ACCOUNT>='600000' AND A.ACCOUNT<'700000')THEN 0 ELSE CREDIT END -
          CASE WHEN (A.ACCOUNT>='500000' AND A.ACCOUNT<'600000') THEN 0 WHEN (A.ACCOUNT>='600000' AND A.ACCOUNT<'700000' AND CREDIT<>0)THEN -CREDIT ELSE DEBIT END) AS 'TOTALE'
FROM (
SELECT BTF1.* FROM BTF1
UNION ALL
SELECT JDT1.* FROM JDT1
) AS A
LEFT JOIN OACT ON (OACT.ACCTCODE=A.ACCOUNT)
LEFT JOIN OBTF ON (OBTF.BATCHNUM=A.BATCHNUM AND OBTF.TRANSID=A.TRANSID)
WHERE A.REFDATE>=@D1 AND A.REFDATE<=@D2 AND (OBTF.BTFSTATUS<>'C' OR OBTF.BTFSTATUS IS NULL) AND (OACT.U_CUENTA<>'' AND OACT.U_CUENTA IS NOT NULL) AND (OACT.U_CUENTA<>'432000000')
GROUP BY A.ACCOUNT, OACT.ACCTNAME
UNION ALL
SELECT  
     A.SHORTNAME AS 'CO.GE ITALIA',
     OCRD.CARDNAME AS 'NOME CO.GE ITALIA',
     SUM(CASE WHEN (A.ACCOUNT>='500000' AND A.ACCOUNT<'600000' AND DEBIT<>0) THEN -DEBIT WHEN (A.ACCOUNT>='600000' AND A.ACCOUNT<'700000')THEN 0 ELSE CREDIT END -
          CASE WHEN (A.ACCOUNT>='500000' AND A.ACCOUNT<'600000') THEN 0 WHEN (A.ACCOUNT>='600000' AND A.ACCOUNT<'700000' AND CREDIT<>0)THEN -CREDIT ELSE DEBIT END) AS 'TOTALE'
FROM (
SELECT BTF1.* FROM BTF1
UNION ALL
SELECT JDT1.* FROM JDT1
) AS A
LEFT JOIN OACT ON (OACT.ACCTCODE=A.ACCOUNT)
LEFT JOIN OBTF ON (OBTF.BATCHNUM=A.BATCHNUM AND OBTF.TRANSID=A.TRANSID)
LEFT JOIN OCRD ON (OCRD.CARDCODE=A.SHORTNAME)
WHERE A.REFDATE>=@D1 AND A.REFDATE<=@D2 AND (OBTF.BTFSTATUS<>'C' OR OBTF.BTFSTATUS IS NULL) AND (OACT.U_CUENTA<>'' AND OACT.U_CUENTA IS NOT NULL) AND (OACT.U_CUENTA='432000000')
GROUP BY A.SHORTNAME, OCRD.CARDNAME
) AS B

Answer 1

Thank you to everybody for your answers.
I need to know more about this way to declare a variable in SAP.
This is my question:
If I need to filter by date a result from a Union All select, is sufficent to declare the Date Variable for one of the two tables in the Union All?
Following a simple code to explain my dubt:
DECLARE @D1 DATETIME
DECLARE @D2 DATETIME
SET @D1='2008/01/01'
SET @D2='2008/02/29'
SELECT A.ACCOUNT, A.DEBIT, A.CREDIT FROM
SELECT * FROM JDT1
UNION ALL
SELECT * FROM BTF1
) AS A
WHERE A.REFDATE>=@D1 AND A.REFDATE<=@D2
Do you think the WHERE statment will continue to run as well for the Union All in the script main too?
This is the modified initial code:
/*SELECT * FROM JDT1 T0*/
DECLARE @D1 DATETIME
DECLARE @D2 DATETIME
/* WHERE */
SET @D1=/* T0.REFDATE */ '[%0]'
SET @D2=/* T0.REFDATE */ '[%1]'
Thanks in advance,
Jonny Cortonicchi