Wireless card shows in Device Manager but says it is disconnected?

This is the second card I have been through that does the same thing.

I install the card, then the software and drivers. After that, I can go into my Device Manager and the card is listed with no errors and the drivers are up-to-date. However, when I click the icon in the bottom right on the taskbar, it shows my card is disconnected and no wireless networks appear.

I have attempted to uninstall and reinstall the device software as well as physically reinstall the card: all yield the same results.

I am running Windows 7 Home 64-bit. I am using a Zyxel pk5000z router provided through Centurylink. The wireless card I am trying to get working is a TP-Link brand TL-WN851ND wireless N, PCI adapter.

There is only one slot on my mobo for the wireless card to fit into, so I am not ruling out that the slot is faulty but at the same time, if it were a bad slot, then I would assume that the card wouldn't even read.