Error Validating Hyper v Machine name Windows 2012 r2? (-1) error

Hi

windows 2008 Server NB 7.5.0.7 Netbackup Master Server

Windows 2012 Server R2 Hyper V Clients NB 7.5.0.7

Host name entry on Master server of all 3 vms include in Hyper V Already added

Now when making policy and adding in Client list it is giving this error

error Validating Hyper v Machine name
Server failed to list VM's (-1)

So how will i resolve this error?

Do i have to install nb7.5.0.6 Special Client agent on Hyper V ? As it is windows 2002 server R2?