There are a number of troubleshooting steps to pursue if you're having this issue:
Have you installed the appropriate driver for them?
What hardware are you using?
Have they ever worked?
What software have you installed so far?
Have you tried them in different PCI slots?
Have you tried them in a different computer?
With answers to these questions I should be able to help you get your hardware installed properly
Elijah Kerry
NI Director, Software Community