@ManyManyBooks: Although I doubt that's the root of the issue, it'll always help to give more accurate info, so start by confirming your exact device model w/ the
WiKi page.
Next, make sure there are no .bin files (or pending OTA downloads) in the USB root of your Kindle, then restart your device, and then try again.
(To explain where I'm going with this: a greyed out "UYK" link usually means that you have the wrong .bin file for your device model. Unfortunately, on FW 5.x, the OTA updater is known to sometimes randomly fall on its ass and fail, or do stupid things, hence the reboot).