Clustering on unicast

HI,

In the user guide its mentioned we can setup clustering on unicast ip

but im not able to see the option to add peer in the interface section in cluster.

e.g

set cluster interface eth1 peer 10.20.1.2 gives the error

configuration path : cluster interface eth1 [peer] is not valid
set failed

How to get this sorted.

Regards
senthil