Agent-state pending in Juju node...NULL public-address associated?

Question

MaaS/Juju does not unfortunately manage the attribution of resolving the IP address. In fact, once adding a new node, it seems that the agent-state is still pending forever, and of course for the other nodes:

 6:
    agent-state: not-started
    dns-name: MaaS03
    instance-id: /MAAS/api/1.0/nodes/node-3550ded6-8be1-11e2-bfa6-0050561dd02a/
    instance-state: unknown
  7:
    agent-state: not-started
    dns-name: MaaS04
    instance-id: /MAAS/api/1.0/nodes/node-bee399c6-8c7d-11e2-aea1-0050561dd02a/
    instance-state: unknown
services:
  ceph:
    charm: local:precise/ceph-91
    relations:
      mon:
      - ceph
    units:
      ceph/6:
        agent-state: pending
        machine: 6
        public-address: null
  glance:
    charm: local:precise/glance-79
    relations: {}
    units:
      glance/0:
        agent-state: pending
        machine: 7
        public-address: null

We can notice that the public-address is always null(???). After disabling the firewall, destroying the env and restarting from scratch, it still isn't resolved.

We have no idea about how it delivers this public-address!? That's a lot of problems with Juju found. It seems quite complicated to see what's wrong.