adobe digital editions!!!! :(

i go to open my book on the kobo and it says "your ereader is not authorized to open this book it is protected by adobe digital rights management. because you previously deauthorized your ereader you need to reimport the book using adobe digital edititons.

i've deactivated/reactivated the kobo and my computer so many tiems and tried to do the same thing over and over...i'm going insane.  what do i do to fix this?!?!