i want ask how can i trace the oracle statement is sql Plus with appliction uses these db

i want explain more about my problem

we have Db Oracle about factory and appliction connect with it using C# and appear some Error message that execute procudure i want trace sql statment throw Sql plus and see all statments done before this Message
and thanx For All

you can enable sql tracing for the session you want
use the following script to get the SID,and serial# for the session you want to trace

SELECT S.sid, S.serial#, S.username, S.osuser,
TO_CHAR(S.logon_time, 'MM/DD/YY HH24:MI:SS') AS "logon_time",
S.status, Lpad(P.spid, 13) AS "spid"
FROM v$session S, v$process P
WHERE S.paddr = + P.addr
ORDER by TO_CHAR(S.logon_time, 'MM/DD/YY HH24:MI:SS')

then execute the following:
execute dbms_system.set_sql_trace_in_session(sid, serial#, TRUE)

after that you can format the output trace file using tkprof