Why wont my stereo read changes from my flashdrive?

Question

I recently bought a sony car stereo which has the USB port in the front. The first time I loaded it it worked fine but now when I try to change the songs on the drive the stereo doesnt read the changes. My computer however reads and records the changes I make, I'm pretty sure the new songs are saved to the device buy my stereo is reading songs that arent even on the flashdrive anymore???

Answer 1

Were the songs in mp3 format when you first tried it and then maybe when you tried new songs they were in wma(windows media player format) or aac(often an iTunes format)? Some head units only read mp3 files.