Hi, Appreciate you response on following matter. I'm adding a new network to a existing cbus network through the 5500NB. there are 7 existing networks and the this is 8th network.they are connected as a star network.PCI is on 2nd network. Once i have connected to the existing network other network getting jammed. eg:- some units are not responding,some groups not getting real feedback to the schedue plus....etc. once it remove the network 8 (new one) all working ggod. what would be the reason?How we could diagnose the issue?? :) regards.