Point grey firefly mv

Hello,
I have 3 cams firewire (point grey firefly mv)
and I would like to see them at the same time…
on the node videoin, i can see and control only 1 of 3…
I had a try to see, at the same time, 3 little handycam (sony,canon) successfully :)
I don’t know why…
Please, someone can help me?
thanx