Unable to retrieve image list on dashboard

My dashboard is installed on my controller node (RHEL6.2) and following services are on the same node:
mysqld
qpidd
openstack-nova-api
openstack-nova-objectstore
openstack-nova-scheduler
openstack-nova-cert

keystone, glance, nova-compute and nova-volume are installed on other nodes.

My local_settings.py like this under the /usr/share/openstack-dashboard/openstack_dashboard/local/:
import os

from django.utils.translation import ugettext_lazy as _

DEBUG = False
TEMPLATE_DEBUG = DEBUG
PROD = False
USE_SSL = False

QUANTUM_ENABLED = False
SWIFT_ENABLED = False

# Note: You should change this value
SECRET_KEY = 'elj1IWiLoWHgcyYxFVLj7cM5rGOOxWl0'

# Specify a regular expression to validate user passwords.
# HORIZON_CONFIG = {
# "password_validator": {
# "regex": '.*',
# "help_text": _("Your password does not meet the requirements.")
# }
# }

LOCAL_PATH = os.path.dirname(os.path.abspath(__file__))

# FIXME: We need to change this to mysql, instead of sqlite.
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'dash',
        'USER': 'dash',
        'PASSWORD': 'dash',
        'HOST': 'localhost',
        'default-character-set': 'utf8'
    },
}

# We recommend you use memcached for development; otherwise after every reload
# of the django development server, you will have to login again. To use
# memcached set CACHE_BACKED to something like 'memcached://127.0.0.1:11211/'
CACHE_BACKEND = 'locmem://'

# Send email to the console by default
EMAIL_BACKEND = 'django.core.mail.backends.console.EmailBackend'
# Or send them to /dev/null
#EMAIL_BACKEND = 'django.core.mail.backends.dummy.EmailBackend'

# Configure these for your outgoing email host
# EMAIL_HOST = 'smtp.my-company.com'
# EMAIL_PORT = 25
# EMAIL_HOST_USER = 'djangomail'
# EMAIL_HOST_PASSWORD = 'top-secret!'

# For multiple regions uncomment this configuration, and add (endpoint, title).
# AVAILABLE_REGIONS = [
# ('http://cluster1.example.com:5000/v2.0', 'cluster1'),
# ('http://cluster2.example.com:5000/v2.0', 'cluster2'),
# ]

OPENSTACK_HOST = "172.16.1.26"
OPENSTACK_KEYSTONE_URL = "http://%s:5000/v2.0" % OPENSTACK_HOST
OPENSTACK_KEYSTONE_DEFAULT_ROLE = "Member"

# The OPENSTACK_KEYSTONE_BACKEND settings can be used to identify the
# capabilities of the auth backend for Keystone.
# If Keystone has been configured to use LDAP as the auth backend then set
# can_edit_user to False and name to 'ldap'.
#
# TODO(tres): Remove these once Keystone has an API to identify auth backend.
OPENSTACK_KEYSTONE_BACKEND = {
    'name': 'native',
    'can_edit_user': True
}

# OPENSTACK_ENDPOINT_TYPE specifies the endpoint type to use for the endpoints
# in the Keystone service catalog. Use this setting when Horizon is running
# external to the OpenStack environment. The default is 'internalURL'.
#OPENSTACK_ENDPOINT_TYPE = "publicURL"

# The number of Swift containers and objects to display on a single page before
# providing a paging element (a "more" link) to paginate results.
API_RESULT_LIMIT = 1000

# If you have external monitoring links, eg:
# EXTERNAL_MONITORING = [
# ['Nagios','http://foo.com'],
# ['Ganglia','http://bar.com'],
# ]

LOGGING = {
        'version': 1,
        # When set to True this will disable all logging except
        # for loggers specified in this configuration dictionary. Note that
        # if nothing is specified here and disable_existing_loggers is True,
        # django.db.backends will still log unless it is disabled explicitly.
        'disable_existing_loggers': False,
        'handlers': {
            'null': {
                'level': 'DEBUG',
                'class': 'django.utils.log.NullHandler',
                },
            'console': {
                # Set the level to "DEBUG" for verbose output logging.
                'level': 'INFO',
                'class': 'logging.StreamHandler',
                },
            },
        'loggers': {
            # Logging from django.db.backends is VERY verbose, send to null
            # by default.
            'django.db.backends': {
                'handlers': ['null'],
                'propagate': False,
                },
            'horizon': {
                'handlers': ['console'],
                'propagate': False,
            },
            'novaclient': {
                'handlers': ['console'],
                'propagate': False,
            },
            'keystoneclient': {
                'handlers': ['console'],
                'propagate': False,
            },
            'nose.plugins.manager': {
                'handlers': ['console'],
                'propagate': False,
            }
        }
}

After I logon the dashboard, there are many errors in the main page like:
Error: Unable to retrieve project list.
Error: Unable to retrieve image list.
Error: Unable to fetch volumes: n/a (HTTP 400)

And in the services page, all the services are identified on localhost and enabled:
nova-volume volume localhost Enabled
glance image localhost Enabled
nova compute localhost Enabled
ec2 ec2 localhost Enabled
keystone identity (native backend) localhost Enabled

Looks like the dashboard can not detect my services on other nodes. Have any configuration items I missed?
I can logon on the dashboard, so looks like the identity is workable for me.