Assist resource and start resource jobs

Hi

I run the job scheduling for a production order, after that 4 jobs are created automatically, some of they are assigned to human resource and some of them are assigned to machine resources.

In the Job Registration form i tried to register as an assistant to a resource which already been assigned a job, but when i click the "start resource jobs", it seems like that nothing happened. is there any additional configuration should be done ?

many thanks