This can be caused by incorrect installation or a resource (IRQ)conflict.
1. Verify that the card is firmly in the slot and seated properly.
2. Verify that the PCI slot is working properly, you may need to enable this in the bios.
3. Check in the Device Manager under Network Adapters to see if the card is installed.
4. Remove the adapter and insert in another free PCI slot.
5. Go to Device Manager and Network Adatpers and check if the card is installed.