Symptoms:

SQL-92: Error (7498) using NULLIF Function in conjunction with the UNION SET OPERATOR.
Invalid number string (7498)
Executing the following SQL-92 query:

SELECT
'stringOne' as 'UNIQUE_ID',
'A' as 'VALUE_STRING',
1.50 as 'VALUE_NUMERIC',
TO_DATE('02-02-2007') as 'VALUE_DATE'
FROM
(SELECT ID FROM SYSPROGRESS.SYSTABLES WHERE TBL = 'Item') dual
UNION ALL
SELECT
'stringTwo' as 'UNIQUE_ID',
NULLIF(-1,-1) as 'VALUE_STRING',
CAST(NULL as FLOAT) as 'VALUE_NUMERIC',
CAST(NULL as DATE) as 'VALUE_DATE'
FROM
(SELECT ID FROM SYSPROGRESS.SYSTABLES WHERE TBL = 'Item') dual