nova-manager operations fail during install

During a fresh install on Ubuntu 12.04 Server, the nova-manage utility nearly always throws up the following error:

DEBUG nova.utils [req-977fa436-86ce-4dc5-9b8b-461dcef45fb9 None None] backend <module 'nova.db.sqlalchemy.api' from '/usr/lib/python2.7/dist-packages/nova/db/sqlalchemy/api.pyc'> from (pid=15952) __get_backend /usr/lib/python2.7/dist-packages/nova/utils.py:658

All updates have been installed and the first instance of this problem occurred while going through the Openstack Install and Deploy Manual from docs.openstack.org, Section 5, Configuring the Database for Compute. The command "sudo nova-manage db sync" was where I first saw this error; subsequent attempts to use the command produced the same error with the following categories:

nova-manage agent list
nova-manage account list
nova-manage db version
nova-manage db sync
nova-manage flavor list
nova-manage network list
nova-manage network create

I assume that there are others that will produce this same result. I also have devstack installed on a VM (VMware Fusion, v4.1.2) running Ubuntu 12.04 Server that has a similar problem:

DEBUG nova.utils [req-18488497-984a-4853-bb68-e3bb441e43c5 None None] backend <module 'nova.db.sqlalchemy.api' from '/opt/stack/nova/nova/db/sqlalchemy/api.pyc'> from (pid=2863) __get_backend /opt/stack/nova/nova/utils.py:569

This was one of the errors that came up from the command "nova-manage -v service list." Most of the other nova-manage commands on that machine state that the table does not exist.

The devstack install is using OpenStack version 2012.2-dev (2012.2-LOCALBRANCH:LOCALREVISION).
The main install is using OpenStack version 2012.1 (2012.1-LOCALBRANCH:LOCALREVISION).

Let me know what other information you need.