I have no idea, but Duokan is a closed-source product made by offsite devs (who incidentally rip off the jailbreak work posted here... without accreditation).
I can however suggest you try
KOReader, an independent project which nevertheless is involved with our community, some of the devs hang out here
and they have a support thread.
Bonus -- it is integrated into the Kindle framework and doesn't require rebooting.