Trigger to enable tracing for user_id problem.

I'm creating a trigger to enable tracing for a particular userid. Yet it seems to enable tracing for ALL userids and ignore my IF clause. I'm hoping someone has an idea.
CREATE OR REPLACE TRIGGER ENABLE_TRACE_ON_DTRAQ AFTER logon ON DATABASE
DECLARE
   p_session_user     varchar2(64);
   p_session_sid      varchar2(64);
   p_session_serial   varchar2(64);
   p_database_name    varchar2(8);
   string_1           varchar2(2000);
  
BEGIN

   /* Set Variables*/
   SELECT UPPER(SYS_CONTEXT('USERENV', 'SESSION_USER')) INTO p_session_user FROM DUAL;
   SELECT UPPER(SYS_CONTEXT('USERENV', 'SID')) INTO p_session_sid FROM DUAL;
   SELECT serial# INTO p_session_serial FROM v$session WHERE SID = p_session_sid;