Problem with query

I have a query with several joins, where I am searching for specific data
in certain columns. If I do this:

SELECT distinct on (s.description, st1.description, s.scene_id)
s.description, s.scene_id, to_char(s.time_of_creation, 'MM/DD/YY
HH24:MI:SS'),
position_0_0_0_info, st.scene_thing_id, si.description,
st.description, m.description
from scenes s
left outer join scene_thing_instances si on s.scene_id = si.scene_id
left outer join scene_things st on si.scene_thing_id =
st.scene_thing_id
left outer join materials m on st.material_id = m.material_id
left outer join scene_things st1 on st.ultimate_parent_id =
st1.ultimate_parent_id
where st.description ilike '%bread%' or st1.description ilike
'%bread%'
group by s.description, st1.description, s.scene_id,
st.scene_thing_id, si.description, m.description order by s.description

No results are found, but if I just do this:

SELECT st.description, st1.description
from
scene_things st
left outer join scene_things st1 on st.ultimate_parent_id =
st1.ultimate_parent_id
where st1.description ilike '%bread%'
group by st.description, st1.description order by st.description

I get the results I expect (several hits).

What is the first query doing wrong?

I've tried adding st1.description to the SELECT list, and the GROUP BY
clause, with no luck.

Thanks,
Susan