Exports from Ableton won't play on CDJs

Hi there.. I keep having an issue where original tracks or re-edits that I make in Ableton Live and export won't play on CDJs.  They work in rekordbox on my computer, but when I put them on a thumb drive, they wont load into the CDJ.  Other tracks that are on said thumb drive play with no problem. I assume that I'm doing something wrong when I export the tracks from Ableton, but I don't have any clue what that might be.  Any help would be greatly appreciated.  thanks!