Turn tracing on for a session

Hi there.

System:

Oracle 8.1.7.0.0 on a Windows 2000 ADV Cluster SP2

I try to turn on the tracing for a session to get tracing info which I can use with tkprof to maybe find out why something takes so long.

So I log in with the client program
then I get the SID and serial# from v$session then I tried
execute dbms_system.set_sql_trace_in_session(sid,serial#,true); then I did the action in the client which takes long, afterwards I did execute dbms_system.set_sql_trace_in_session(sid,serial#,false);

in the udump directory (in v$parameter) I dont get any new tracefiles. Shouldnt there be a new trace file?

I also tried
execute dbms_support.start_trace_in_session(sid,serial#,true,true); and a
execute dbms_support.stop_trac_in_session(sid,serial#);

no new file either.

I dont get any errors. It says thtat the PL/SQL has been run sucessfully.

I also tried to rerun dbmsutil.sql and prvtutil.plb in case the grants and/or public synonyms havent been created .. but it didnt help.

Any idea what I am making wrong here?

-- 
mfg
Marc Eggenberger