Render Server

Hi Everyone.
I cant seem to figure out how i can assign the rendering to only a specified server? for instance render-07?
the code works fine but it does not submit the job to the specified server only to render
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man = netrender.getmanager()
man.connect #manual "localhost"
job = man.newJob() -- current scene
job.useAllServers = false
job.suspended = true
job.specific_servers = #( "render-07", "render-09" )
job.submit()
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any help would be appreciated.
thanks