MAJOR Problem! (I think)

The following query works perfectly in V5.6 and does not in free version
6.01:

GLAMT is defined via domain "MONEY":
CREATE DOMAIN MONEY AS DOUBLE PRECISION DEFAULT 0;

I have a stored proc that runs the following:
/***********************************************/
INSERT INTO GENERAL_LEDGER (
COMPANY, DIVISION, GLNO, SALESCOSTOF, POSTINGDATE,
SOURCE, GLAMT, ENTEREDBY, ENTEREDSYSTEM, BatchID)
SELECT
COMPANY, DIVISION, GLNO, SALESCOSTOF, POSTINGDATE,
SOURCE, GLAMT, :InUserID, ENTEREDSYSTEM, :InBatchID
FROM GENERAL_LEDGER_BE
WHERE
BatchType = :BatchType and
UserID = :InUserID and
Company = :InCoNo and
Division = :InDivNo and F_FIXEDPOINT(GLAMT,2) <> 0;
/***********************************************/

Version 5.6 works and inserts 2 records into my general ledger. V6.01 does
not!
One can see where this would be HUGE problem for accountants!
If I remove the F_FIXEDPOINT(GLAMT,2) from the comparison, V6.01 then does
work:

INSERT INTO GENERAL_LEDGER (
COMPANY, DIVISION, GLNO, SALESCOSTOF, POSTINGDATE,
SOURCE, GLAMT, ENTEREDBY, ENTEREDSYSTEM, BatchID)
SELECT
COMPANY, DIVISION, GLNO, SALESCOSTOF, POSTINGDATE,
SOURCE, GLAMT, :InUserID, ENTEREDSYSTEM, :InBatchID
FROM GENERAL_LEDGER_BE
WHERE
BatchType = :BatchType and
UserID = :InUserID and
Company = :InCoNo and
Division = :InDivNo and GLAMT <> 0;

/***********************************************/
Is this a bug in V6.01 or should UDFs not be used in a Where clause?????

All replies will be much appreciated.

Kevin