What userid to run dbms_system.set_sql_trace_in_session from?

I have been able to successfully run dbms_system.set_sql_trace_in_session from sqlplus prompt as system user. I put in the correct SID and serial number and TRUE
and everything seems fine. Response is that it appears to have run correctly. Then I run it again with FALSE to turn off trace. Response is that everything seems
to be fine. But when I go to the udump directory, no trace file has been generated.

I know it is the correct udump directory because if I turn on trace for my session and
run a query and then turn off trace, a trace file is correctly generated in the same
udump directory.

Why might I not be getting a trace file generated on the session that is running?
Do I have to log in as the user that was running the job in order to run dbms_system.
I was running from SYSTEM.

Or is it something else? Received on Fri Aug 11 2000 - 15:55:25 CDT