Automation plans Available targets empty

Hello, I started playing with deployment plans this week and I cannot figure how to make one work.
I created a custom site inside the Server Automation site
this site contains one task
this site has subscribed all the servers in the farm
the task uses some perl scripts and some relevance which means only 9 servers are available at run time.
I am able to run the task on its own and it works like a charm.
I go to automation plans
click on create
type the name of the automation
in steps I add a step and I find the given task
Click on the system icon
on the targets tab two options are available
Specify computers select in the list below
The computers specified in the list of names below (one per line)
left the first option checked
there is a line by the list of targets (which is empty) that reads Use applicability (9/312) and it got a grey out check mark
Now my problem is that it does not matter what I do, I can not make any targets appear on the available targets or selected targets…

what am I missing, why if the task already knows that only 9 servers are applicable, why are thy not showing or do they have to show at all?

Thanks.