I've got a Sony PRS-350 that I bought and recently was told by a company that I bought an eBook from that I needed to use adobe digital editions to read it. But when I plug the ereader into my computer, it does not show up in my bookshelf tab, though it appears on my macbook's desktop.
I'm not an expert in MAC, but if this were a PC, you might be experiencing
a 'timing' issue. Try this: make sure the Macbook sees your ereader as a
device, THEN start ADE.
I can't believe this question has not been answered since 2011!
I have the same issue with my Sony e-reader. No device shows up in my ADE program, and so I cannot transfer my legally bought e-books to my e-reader.