That means there's no guide data available for that station in that zip code. IF there's a another station in the list that matches the network, Cbs, ABC, etc, try picking one of those.
If that doesn't work, try switching to another LOCAL zip code nearby, that has those stations. I myself have to use a zipcode from a city that's 15 miles away. IF I use my exact local zip code, it doesn't pick up all my stations.
Top LEFT corner on the Manage screen, shows the zip code it's using. Click the +, and try another one. Wait until the new guide populates. IF you are lucky, you'll find one that works to get the new channels, without losing any of your other channels.