A brief (for me) mea culpa: Just before I released 1.0, I moved the activation hook code (which creates the Seller role and capabilities) to it’s own file, not knowing that this would fail miserably. Everything else works just fine in it’s own file, so why not the activation hook? But I guess I forgot to start with a fresh database before testing that change, because the role was there, so I figured it all worked.
But, alas, it didn’t work, which I just discovered a couple days ago. So after some research (boy, there are a LOT of forum posts about this problem), I got it to work again. Yippee!
So today I released version 1.1, which does what it should on activation.