Originally posted by slimdave
have you run catxplan.sql?
for 9i this is not enougth.
U have to create plustrace role (as sys) and grant this role to user.
Code:
CONNECT / AS SYSDBA 
@$ORACLE_HOME/SQLPLUS/ADMIN/PLUSTRCE.SQL 
GRANT PLUSTRACE TO ....(user_name)...;