set autotrace traceonly explain then - 'PLAN_TABLE' is old version

Hello gurus,
     I would like analyze several queries because it's seemes i have times response very then when i execute :
     The version of my database is 11.2.0.3 :

     SQL>   set autotrace traceonly explain
     SQL> my query therefore i have :
               Note
               -----
               - 'PLAN_TABLE' is old version

>>>> i tried to execute $ORACLE_HOME/rdbms/admin/catplan.sql
and i executed again and again i have the message above.

My query and the result :

select VENDOR_ID, count(VENDOR_ID), PREPAY_ID, count(PREPAY_ID) FROM AP_UNAPPLY_PREPAYS_FR_PREPAY_V group by VENDOR_ID, PREPAY_ID;

Execution Plan
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| Id  | Operation                                | Name                         | Rows  | Bytes | Cost (%CPU)|