VM stuck in PENDING state in Opennebula 5.0.2 (Ubuntu 14.04)

I couldn’t deploy or recover it either. What should i do now to make it running?
Error Messages:

VM State now:
Host column shows empty now,

Hi,

Your cluster needs to have at least one system DS. More info here:
http://docs.opennebula.org/5.0/operation/host_cluster_management/cluster_guide.html#the-system-datastore-for-a-cluster