MacOS – Why is the Advanced Add Printer mode disabled

I am using a Unibody MacBook Pro on Lion. I am trying to add a networked printer at work so I can print to it, but OS X is not cooperating with me.

Typically for adding networked printers on a Windows network, most instructions online suggest you open the Print & Fax preference pane, hit the + button to Add Printer, then use the Advanced tab to select the type of networked printer, and type in a specific URL to reach it.

I would like to follow these steps, but I am unable. As you can see in the screenshot below, everything under the Advanced tab in the Add Printer window is disabled.

I don't understand how or why this is. My user definitely has full administrator privileges, and this tab of all the others in the dialog should be open-ended and allow you to type and search for printers to add regardless of environment, or perhaps what OS X may have already detected as plugged-in or over Bonjour.

I have searched the web for any indication of why this area of my Add Printer dialog is unusable, but have not been able to find any clues. Any tips to get this thing unstuck are appreciated.

P.S. My connection to the Windows network at work seems to be fine. I am able to mount and use several of the shared network drives over SMB.