Using a CFQUERYPARAM list IN stmt not working

I have a query I am running against an Oracle 9i db that has to check a list of codes.

The query listed at the bottom of this post returns expected results using
AND fec.ERROR_CODE IN (# PreserveSingleQuotes(errCodeList)#)

If I try to use
AND fec.ERROR_CODE IN (<CFQUERYPARAM list="yes" value="#errCodeList#"> )
the query returns 0 rows.

OK, here's the "intersting"part. If I change
IN (<CFQUERYPARAM list="yes" value="#errCodeList#"> )
to
NOT IN (<CFQUERYPARAM list="yes" value="#errCodeList#"> )
passing the same exact list the query returns rows!!! I get the opposite results I want, but the query still returns rows. I'm passing the same exact list to the query whether I use PreserveSingleQuotes, CFQUERYPARAM and using both IN and NOT IN constraints.

Why does NOT IN work and IN fail for the same list? Yes, the data is there, I have (at least) triple-checked.

The output from CF debug I get when using CFQUERYPARAM:
SELECT DISTINCT f.field_name,
f.label,
f.field_id,
f.input_type,
f.ERROR_CODE ,
gf.sort_order
FROM group_field gf,
FIELD f,
field_error_code fec
WHERE gf.GROUP_ID = (SELECT GROUP_ID FROM form_group WHERE form_id = ?)
AND gf.field_id = f.field_id
AND f.field_id = fec.FIELD_ID
AND fec.ERROR_CODE IN (?,?,?,?)
ORDER BY gf.sort_order

Query Parameter Value(s) -
Parameter #1(cf_sql_varchar) = FORM_NAME
Parameter #2(cf_sql_varchar) = '130'
Parameter #3(cf_sql_varchar) = '131'
Parameter #4(cf_sql_varchar) = '132'
Parameter #5(cf_sql_varchar) = '133'

It appears a single-quoted, comma-delimted list is being passed to the db for the query.

Any help anyone can give will be greatly appreciated!