problem importing wavs inot rekordbox

been using rekordbox for couple of years, tried to add a bunch of wavs today just downloaded from juno and got this message i've never seen before: "some tracks will not be exported. rekordbox export tracks playable on the pioneer dj players" and it wouldn't add any tracks to my playlist, don't think i've done anything any different from normal other than recently upgrading to version4, went back and tried on version3 and same message - any ideas please?