Interactive Report column visible but cannot filter

Question

I have a complex interactive report running on Oracle 10gR1 using Apex 3.1
When I display the report, all the desired columns are visible. However, when I try to do a filter on a particular column it does not appear in the column filter list even though it is visible in the Select Column list. All the other report columns are available in the filter list.
The specific column is the result of a join and a substitution within the SQL select. The problem column is 'file_nm'. I've bolded the line in the script below.
Any suggestions?
Thanks,
George
Here's the IR sql:
WITH joined_data AS
( SELECT a.fdno fdno
, a.site_abbrv_cd site
, a.season
, a.find_id
, a.dig_ctgy_cd dig_ctgy
, a.find_ctgy_cd find_ctgy
, a.materials_qstnbl_ind matl_qstnbl
, a.color
, a.field_obj_type_nbr field_type_nbr
, a.is_inscribed_ind is_inscribed
, a.display_seq_nbr seq_nbr
, n.img_file_nm file_nm
, h.material_descr
, g.general_matl_ind primary
, g.specific_matl_ind secondary
, i.keyword
, i.kw_cls
, i.lvl_nbr
, j.kw_descr
, b.site_subdiv_type_cd AS type
, b.site_subdiv_nm AS nm
, CONCAT(b.sq_h_coord, CONCAT(b.sq_v_coord,
CONCAT(':', b.locus_nbr))) AS locus
FROM find a
LEFT OUTER JOIN ref_item_assoc m ON a.find_id = m.obj_id
AND m.deflt_dsply_img_ind = 'Y'
LEFT OUTER JOIN digital_img n ON m.ref_item_id = n.ref_item_id
LEFT OUTER JOIN find_site_subdiv ab ON a.find_id = ab.find_id
LEFT OUTER JOIN site_subdiv b ON ab.site_subdiv_id = b.site_subdiv_id
LEFT OUTER JOIN keyword_assocn i ON a.find_id = i.obj_id
LEFT OUTER JOIN keyword j ON i.keyword = j.keyword
AND i.kw_cls = j.kw_cls
LEFT OUTER JOIN material_find g ON a.find_id = g.find_id
LEFT OUTER JOIN material h ON g.material_cd = h.material_cd
SELECT site
, find_id
, season
, fdno
, matl_qstnbl
, CASE WHEN color IS NOT NULL THEN color ELSE 'No entry' END AS color
, CASE WHEN field_type_nbr IS NOT NULL THEN field_type_nbr ELSE 'No entry' END As Field_type_nbr
, is_inscribed
, seq_nbr
*, MAX (CASE WHEN file_nm IS NOT NULL THEN 'Y' ELSE 'N' END) AS file_nm*
, MAX (CASE WHEN type = 'AR' THEN nm ELSE 'No entry' END) AS Area
, MAX (CASE WHEN type = 'AL' THEN nm ELSE 'No entry' END) AS A_Level
, MAX (CASE WHEN type = 'LO' THEN locus ELSE 'No entry' END) AS Locus
, MAX (CASE WHEN kw_cls = 'FI_CTGY' THEN kw_descr ELSE 'No entry' END) AS find_ctgy
, MAX (CASE WHEN kw_cls = 'FI_DIGCTGY' THEN kw_descr ELSE 'No entry' END) AS dig_ctgy
, MAX (CASE WHEN primary = 'Y' THEN material_descr END) AS Primary
, MAX (CASE WHEN secondary = 'Y' THEN material_descr END) AS Secondary
, MAX (CASE WHEN (kw_cls = 'FI_DESCR' AND lvl_nbr = 1) THEN keyword ELSE 'No entry' END) AS descr1
, MAX (CASE WHEN (kw_cls = 'FI_DESCR' AND lvl_nbr = 2) THEN keyword ELSE 'No entry' END) AS descr2
, MAX (CASE WHEN (kw_cls = 'FI_DESCR' AND lvl_nbr = 3) THEN keyword ELSE 'No entry' END) AS descr3
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 1) THEN keyword ELSE 'No entry' END) AS DescrN_1
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 2) THEN keyword ELSE 'No entry' END) AS DescrN_2
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 3) THEN keyword ELSE 'No entry' END) AS DescrN_3
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 4) THEN keyword ELSE 'No entry' END) AS DescrN_4
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 5) THEN keyword ELSE 'No entry' END) AS DescrN_5
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 6) THEN keyword ELSE 'No entry' END) AS DescrN_6
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 7) THEN keyword ELSE 'No entry' END) AS DescrN_7
, MAX (CASE WHEN (kw_cls = 'FI_DESCRN' AND lvl_nbr = 8) THEN keyword ELSE 'No entry' END) AS DescrN_8
, MAX (CASE WHEN (kw_cls = 'ARCH_CNTXT' AND keyword IS NOT NULL) THEN keyword ELSE 'No entry' END) as arch_cntxt
FROM joined_data
GROUP BY site, find_id, season, fdno, matl_qstnbl, color, field_type_nbr, is_inscribed, seq_nbr
ORDER BY seq_nbr

Answer 1

Look at the interactive report Column Attribute, Allow Users to Filter check box might not be checked for this column. Thanks.
--Manish