When you say refuses to communicate, what do you mean? Can you ping through it? Can you telnet through it? If you can't, is it installed correctly and configured in the OS? Has a firewall (either SW or HW) blocked communication?
If you can communicate with other applications, just not LabVIEW, you might still check firewall settings. Other than that, I have not tried to use two network cards before, so I don't really know what all you need to change to make LabVIEW use the second.
