Problems removing ePub DRM with Adobe Digital Edition in Linux Ubuntu 10.10

[MassimoA]

Hello everyone,
my computer running Linux Ubuntu 10.10, and would like to install on my new Kindle 3 the book i will buy online (Amazon still has too few books in Italian).
I found the guide, very interesting, in order to install the DRM ePub (http://stream-recorder.com/forum/dow...ve-t7955.html), but unfortunately I can not see the book, a window appears that warns you that it is impossible to proceed (see screeshot).

How to resolve?

Best Regards
Massimo