Firewire Card - Adaptec AFW-2100 - Installation Issue

My friend recently purchased a new Dell desktop with firewire as part of the bundle.  However, he soon got a better USB/1394 pci card, and gave me the Adaptec card that came with computer to install. 

 

I have installed the card, but cannot get my dimension 4300 to recognize the pci card. When I scan for new hardware, it can't find anything new, and I'm certain that it's properly fitted in the slot.  Have tried moving to different slots with no success.

 

As Dell does not expect anyone to be trading these spare parts, can't find any documentation to really help. Wondering if anyone has any thoughts on what could be wrong, or how to proceed.  In the end I don't really mind spending $40 for a new card, but am curious why this isn't working...