1. is it an expansion card that you have added into the pc, a desktop?
if so, are there many pci or pci-e card slots to put it in and try?
2. is it a laptop with a mini firewire connection, and firewire is built in?
3. in either case, windows xp 7 8 and 8.1 need drivers to see firewire usually.
laptop: goto the web and download the drivers for firewire for your laptop model #
desktop: look at the pci or pci-e card and download the drivers for that card
4. run the drivers, and then firewire should show up if installed properly. restart after installing.
Possible problems
1. bad cable, the firewire cable is damaged
2. bad port for firewire, it is broken or bent in the computer or camera and no signal is being sent
3. old drivers, so it will not install xp drivers for windows 7 etc
