Natural 2.2.8 is about 12 - 14 years out of support. However, if you are encountering errors, it is usually helpful to include the error messages you are getting. At this point, we have no way to tell if you have a simple syntax error, typo, missing DDM, incorrect field name, database down…So, start with what the error message(s) are telling you and correct those.
If you’re really lost, try posting the program (if less than ~100 lines) or significant snippets of it so we can give some guidance - perhaps you are missing data definitions from the DEFINE DATA area? You need to include different “LOCAL USING xx” where “xx” is a local data area name containing the data definitions for your tables? Or the program has no DEFINE DATA (suggesting a “reporting mode” program), then you need to find the DDM for the tables you are trying to unload: can you do a “LIST FILE tablename” at a NEXT prompt? If not, your Natural Administrator will have to make the DDM available to you.