One Db Scheduled Job (With Db Queue), the Attribute parallel_instances has some wrong in RAC.

We are going to make the RAC (Two Nodes) from Standalone Instance, we have Db Scheduled Jobs (With Db Queue), we set the Attribute parallel_instances as True due to the needs of our business.

e.g. as below

begin dbms_scheduler.set_attribute('xxxx','parallel_instances',TRUE);end;/

Submitting a single or multiple queues in instance 1, it CAN NOT trigger scheduler job created on instance 2. ===================================================================

So any aspects we need to consider for the Db Scheduled Jobs and Queue in RAC? Thanks.