Some USB-loaded books won't open on new Kindle 4

Hi all,

My Kindle 4 recently died, I bought a refurbished one, and I'm trying to load my library. Some of my books open just fine on the new device, but some give me the message "This item cannot be opened because it is licensed to a different user. Delete the item and download it from your Archived items or purchase a copy from the Kindle Store." My new Kindle is registered to my Amazon account, so I'm not sure why I'm getting that message. I also have the deDRM packages installed, so I'm also confused why the content is getting flagged in the first place.

Thank you for the assist

EDIT: I seem to have fixed this issue by running convert on the troublesome files from az3 format to mobi and sending the mobi version back to the device