Power Management - no running proxy Host was found

Issue

Trying to configure Power Manager on RHEV-H returns error message on RHEV-M console :

Test failed. Host status is unknown. The fence agent scripts reported the following error. There is no other host in data center that can be used to test the power management settings.

In log file /var/log/rhevm/rhevm.log

ERROR [org.ovirt.engine.core.bll.FencingExecutor] (http-0.0.0.0-8443-2) Failed to run Power Management command on Host , no running proxy Host was found.