I'm having problems getting my USB stick with music to work. When I plug it in, it says it is detected then I just get the AUX screen. I tried pressing the AUX button to cycle through (as it says to do in the manual) but no joy. It's a 8Gb SanDisk stick. I reformatted it as FAT32 and loaded a couple of music tracks on it but can't get it to work. Any thoughts anyone?