Cannot create sql tunning task

Hi everyone, i want to create a SQL tunning task to use sql access advisor

Im using this query

SET SERVEROUTPUT ON

declare

stmt_task VARCHAR2(40);

begin

stmt_task := DBMS_SQLTUNE.CREATE_TUNING_TASK(sql_id => '5tru8vxmktswq');

DBMS_OUTPUT.put_line('task_id: ' || stmt_task );

end;

/

but i got this errors:

ORA-13780: SQL statement does not exist.

ORA-06512: at "SYS.DBMS_SYS_ERROR", line 79

ORA-06512: at "SYS.PRVT_SQLADV_INFRA", line 116

ORA-06512: at "SYS.DBMS_SQLTUNE", line 572

ORA-06512: at line 4

My Oracle Database is 11.1.0.7 Enterprise Edition

Regards.