Gig tonight, need help!

Hey guys, 

i just bought some new songs in itunes and did my normal routine. (put them through mixed in key, create and update my itunes playlists, rated the songs within itunes) 

I just opened rekordbox (5.6.0) and wanted to update my USB-Drives for tonight. But all the new songs (all of them are .m4a) don't have a rating in rekordbox. 

i don't import the songs to rekordbox. I just use rekordbox to synchronize my USBs. 

I have the "share xml data"-thing  in the itunes prefenrences enabled. 

Does anyone has an idea? Doesn't it work with .m4a any more?