Can't record in GB 10 - keeps telling me no input source is selected
I'm attempting to use GarageBand 10 for my podcast, which isn't a happy experience, since they've removed some features that were helpful for podcasting, and made some changes which I think make it more cumbersome to use for any purpose. If I knew an affordable program that I could put my show together in more easily than GB, I would gladly switch to it and abandon this very disappointing GB version.
Although initially I was able to record voiceovers directly into GB, lately it refuses to record anything. It pops up a "No input source selected!" message, but then pretends to record anyway until I click the stop button -- at which point, it again tells me "No input source selected!" and then ceases to pretend-record.
In the Preferences, there is indeed an input source selected. So why is it giving me this popup?
GarageBand (Mac) '11, OS X Mavericks (10.9.1)