Is the "Airport Extreme Upgrade for Mac Pro" compatible with early Mac Pros

I just purchased the "Air Port Extreme Wireless Upgrade Kit" MB988Z/A, and installed it my self into my early 2008 Mac Pro (Early 2008). System Preferences and Network utility report it as there, but when scanning it does not pick up any wireless networks?

I am trying to pick up an existing, and known good, wireless signal that my (other Mac) iMac picks up fine. It is a Verizon modem/router (802.11b/g), and I also have a Linksys 802.11n router; but neither are picked up by the scans.

I think the card is defective...ugh. Any suggestions?