I am installing Openstack (Queens) using Packstack. When I install components of Openstack, I am getting the following error continuously:

192.168.122.x.y_network.pp: [ ERROR ] Applying Puppet manifests [ ERROR ]

ERROR : Error appeared during Puppet run: 192.168.x.y_network.pp Error: /Stage[main]/Packstack::Provision::Bridge/Neutron_l3_ovs_bridge[demo_bridge]: Could not evaluate: Can't retrieve subnet-list because Neutron or Keystone API is not available.

Could you please help me out on how to proceed further? I have tried almost every documentation on the net.

PS : I am running Openstack on a CentOS 7 Virtual Machine.

Thanks