Do you get the errors when connecting to the Vicon server using a non-clustered script? The current behavior is a bug in the Vicon plugin. In cluster mode, only the master should connect to the server. This will be fixed in the next release.
As a workaround, try the following code which will only load the Vicon plugin on the master computer and loads a dummy extension (VRPN) on the clients:
Code:
viz.cluster.setMask(viz.MASTER)
vicon = viz.add('vicon.dle',...) #Create vicon plugin on master
viz.cluster.setMask(viz.ALLCLIENTS & ~viz.MASTER)
viz.add('vrpn7.dle') #Create dummy extension on clients
viz.cluster.setMask(viz.ALLCLIENTS)