Lab 3.2 use script to join hypervisor to cloud

Hi, on lab 3.2 i am getting an error when running the ./tools/disocver_hosts.sh command, here is the output below, any ideas?

An error has occurred:

Traceback (most recent call last):

  File "/opt/stack/nova/nova/cmd/manage.py", line 1863, in main

    ret = fn(*fn_args, **fn_kwargs)

  File "/opt/stack/nova/nova/cmd/manage.py", line 1583, in discover_hosts

    hosts = host_mapping_obj.discover_hosts(ctxt, cell_uuid, status_fn)

  File "/opt/stack/nova/nova/objects/host_mapping.py", line 206, in discover_hosts

    cell_mappings = objects.CellMappingList.get_all(ctxt)

  File "/usr/local/lib/python2.7/dist-packages/oslo_versionedobjects/base.py", line 184, in wrapper

    result = fn(cls, context, *args, **kwargs)

  File "/opt/stack/nova/nova/objects/cell_mapping.py", line 137, in get_all

    db_mappings = cls._get_all_from_db(context)

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 978, in wrapper

    with self._transaction_scope(context):

  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__

    return self.gen.next()

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 1028, in _transaction_scope

    context=context) as resource:

  File "/usr/lib/python2.7/contextlib.py", line 17, in __enter__

    return self.gen.next()

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 633, in _session

    bind=self.connection, mode=self.mode)

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 398, in _create_session

    self._start()

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 484, in _start

    engine_args, maker_args)

  File "/usr/local/lib/python2.7/dist-packages/oslo_db/sqlalchemy/enginefacade.py", line 506, in _setup_for_connection

    "No sql_connection parameter is established")

CantStartEngineError: No sql_connection parameter is established