[ubuntu] problem with authentication via SSH on MaaS Nodes

hi everyone, i need to resolve a problem with MaaS server, after have added the nodes, changed the their status to ready, added ssh key, started the ubuntu's installer, boot the nodes from their HD.....
when i try to make the login via ssh on the nodes they ask me the password.
i've also try to modify the parteed file added a pwd in md5 but nothing.
is there someone can help me, please?