RB dosn`t sync the complete collection /HELP

hello

ive a problem, i deleted my SD CARd today and synced it once again, but rekordbox 1.5.0 dosnt sync the complete collection, im missing about  20 tracks... but its very difficult to find out which tracks are missing i`ve a collection about 900 tracks... but i think, if i have a clean SD Card, Rekodbox should sync the complete collection and i should have the same tracks on my sd card as in my collection, or ?

so anyone got the same problem allready? 

need some help, thank