ORA-00922: missing or invalid option

Hello all,
     I think this is the most suitable community to make the question.
I've a problem creating a structure of queue tables.

The error is:

     ORA-00922: missing or invalid option

And the script is:

     DECLARE
       subscribers sys.aq$_agent;
     BEGIN
       subscribers := sys.aq$_agent ('subscriber1', null, null);
       DBMS_AQADM.CREATE_QUEUE_TABLE (Queue_table => 'JMS_EVENTOS', Queue_payload_type => 'SYS.AQ$_JMS_TEXT_MESSAGE', multiple_consumers=>true);
       DBMS_AQADM.CREATE_QUEUE (Queue_name => 'JMS_COLA_EVENTOS', Queue_table => 'JMS_EVENTOS');
       DBMS_AQADM.add_subscriber(queue_name=> 'JMS_COLA_EVENTOS', subscriber =>subscribers);
       DBMS_AQADM.START_QUEUE (Queue_name => 'JMS_COLA_EVENTOS');