Did you declare the port number the flock is connected on and the number of birds that are connected? For example, if you were connecting to 2 birds on port 1 you would do the following:
Code:
PORT_FOB = 1
NUM_FOB = 2
flock1 = viz.add('flockofbirds.dls')
flock2 = viz.add('flockofbirds.dls')