Tree doesn't show up in the page (apex 4.0.2.00.07)

Question

Hi,
I have created a tree region in the page in my application on apex.oraclecorp.com(apex 4.0.2.00.07), the query itself works well in the "SQL Commands", but the tree does NOT display in the page at all. Any comments will be very much appreciated.
The result of the query in "SQL Commands" is as below:
STATUS      TITLE      ICON      VALUE      TOOLTIP      LINK
1      Event Docs      -      Event Docs      Event Docs      -
-1      2011      -      2011      2011      -
-1      test event 01      -      test event 01      test event 01      -
0      test_pdf.pdf      -      test_pdf.pdf      test_pdf.pdf      -
0      test_xls.xls      -      test_xls.xls      test_xls.xls      -
0      test_xls.zip      -      test_xls.zip      test_xls.zip      -
And the query is like below:
with v as
( select d.ATTACH_FILENAME name, e.event_name parent, d.doc attr
from rw_docs d,
rw_int_event_doc ied,
rw_events e
where d.doc_id=ied.doc_id
and ied.event_id=e.event_id
union all
select e.event_name name, to_char(extract(year from e.start_time)) parent, null attr
from rw_events e
union all
select to_char(extract(year from e.start_time)) name, 'Event Docs' parent, null attr
from rw_events e
union all
select 'Event Docs' name, null parent, null attr
from dual)
select case when connect_by_isleaf = 1 then 0 when level = 1 then 1 else -1 end as status,
name as title,
NULL as icon,
name as value,
name as tooltip,
NULL as link
from v
start with parent is null
connect by prior name = parent
order siblings by name

Answer 1

check the DB version compatibility with apex 4 or your DB version to apex 4.0 support for upgrade!
Oracle Application Express Installation Requirements for 4.0