I have the exact same problem and needless to say, I am really pissed off!!!
Such technology should not have compatibility problems, either your reader can download ebooks or else it should not be sold as an ebook reader.
I've had to download a DRM removal tool in order to read ebooks that I PAID FOR on a regular e-reader that I REGULARLY BOUGHT!!!
The problem is, not all e-books can get unlocked so I already have 4 books I can't read except on my PC.