Temp Tablespace

Guys,  

I have a database that has 16GB of allocated data on the temp database even though there is no one accessing it. I had shutdown/started it. How can I reclaim this space? When I try alter database tempfile '...' RESIZE 15000M, it says that there is data beyond that point.  

Thanks  

SELECT s.sid "SID",s.username "User",s.program "Program", u.tablespace "Tablespace",

u.contents "Contents", u.extents "Extents", u.blocks*8/1024 "Used Space in MB", q.sql_text "SQL TEXT",

a.object "Object", k.bytes/1024/1024 "Temp File Size"

FROM v$session s, v$sort_usage u, v$access a, dba_temp_files k, v$sql q

WHERE s.saddr=u.session_addr

and s.sql_address=q.address

and s.sid=a.sid

and u.tablespace=k.tablespace_name;    

--
http://www.freelists.org/webpage/oracle-l