I just started using Adobe Digital Edition several days ago with version 1.5. And there is a "ebx_backup" folder under "My Digital Editions" which stores the automatically backed-up ebooks files. But yesterday, after i download the new version 1.6 and purchased several others new ebooks afterward, they are no longer automatically backed up and doesn't appear in the "ebx_backup" folder. Is it a bug? How can i solve it? Or can i manually move the .pdf ebooks from "My Digital Editions" to "ebx_backup" folder?