使用者autotrace 無法使用解決

SQL> set autotrace on
SP2-0618: Cannot find the Session Identifier.  Check PLUSTRACE role is enabled
SP2-0611: Error enabling STATISTICS report
SQL> conn / as sysdba
Connected.
SQL> grant plustrace to scott;
grant plustrace to scott
      *
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist
SQL> @$ORACLE_HOME/sqlplus/admin/plustrce.sql
SQL> 
SQL> drop role plustrace;
drop role plustrace
          *
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist
SQL> create role plustrace;
Role created.
SQL> 
SQL> grant select on v_$sesstat to plustrace;
Grant succeeded.
SQL> grant select on v_$statname to plustrace;
Grant succeeded.
SQL> grant select on v_$mystat to plustrace;
Grant succeeded.
SQL> grant plustrace to dba with admin option;
Grant succeeded.
SQL> 
SQL> set echo off
SQL> grant plustrace to scott;
Grant succeeded.
SQL> conn scott/oracel
ERROR:
ORA-01017: invalid username/password; logon denied
Warning: You are no longer connected to ORACLE.
SQL> conn scott/oracle
Connected.
SQL> set autotrace on;
SQL> select * from emp2 where empno=7788;
     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM
---------- ---------- --------- ---------- --------- ---------- ----------
    DEPTNO
----------
      7788 SCOTT      ANALYST         7566 19-APR-87       1212
        20
Execution Plan
----------------------------------------------------------
Plan hash value: 4075136777

| Id  | Operation                   | Name     | Rows  | Bytes | Cost (%CPU)| Ti
me     |

--------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |          |     1 |    87 |     2   (0)| 00
:00:01 |

|   1 |  TABLE ACCESS BY INDEX ROWID| EMP2     |     1 |    87 |     2   (0)| 00
:00:01 |

|*  2 |   INDEX RANGE SCAN          | EMP2_IND |     1 |       |     1   (0)| 00
:00:01 |

--------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
   2 - access("EMPNO"=7788)
Note
-----
   - dynamic sampling used for this statement (level=2)
Statistics
----------------------------------------------------------
        152  recursive calls
          0  db block gets
         23  consistent gets
          0  physical reads
          0  redo size
        868  bytes sent via SQL*Net to client
        419  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          1  rows processed