I have found that having a space between > and = is valid SQL syntax, but is rejected by RES.
I can easily fix it by removing the space, but just for completeness thought I would raise the issue (expecting the fix will be quite easy for you).
FROM RATINGMETHODUSE A,
WHERE A.PRODUCTID = :SV-Q-PRODUCTID
AND (C.DATEDEACTIVE > =
OR C.DATEDEACTIVE IS NULL)
I get the following rejection message.
com.res.cobol.parser.ParseException: Encountered " ">" "> "" at line 548, column 48.