Hi,
the network detection within failover cluster is automatically done by NETFT (Topology Manager) which discovers your networks and adds 1 network per subnet to your cluster. Do you have used an different subnet for your new added HB network? normally the
network will be added auto
http://blogs.technet.com/b/askcore/archive/2009/02/13/what-is-a-microsoft-failover-cluster-virtual-adapter-anyway.aspx
already validated your network?
PS: just an reminder, in windows 2008 you normally don't need an dedicated HB nentwork anymore, just to have multiple networks on your cluster would be generally enough,.
Regards
Ramazan
Ramazan Can [MVP Cluster] http://ramazancan.wordpress.com/