Thanks for your answer.
I tested to do a netserver package for my servers and it worked fine. Thank you for the tip !
I still having problems with the licences. If old computers in the AD were using licences, they are supposed to be in black with an old date in the field "last communication", but it's not the case.
I have a total of 41 computers with agent and no more, all the others are grey or with a key, even if some of them got the netclient.
It's a bit strange :s
Thanks by advance for any help !