Network card not detected on netwrok

I have genius New GE2000111 series network cards installed in in pc that are using a peer to per network with a BNC connetion type. I have been using the network for more than a year until now.
On four of the pcs the cards can be detected but if you try to log on the netwrok from a defferent pc , it is not detected
If I put a deffernt card , it detectc it withno problems at all
Could it be the network cards that are faulty or its something else

Herby