Hi! I have a problem with my new LK-280. I can't seem to be able to play the songs I put on my SD Card. I've put the midi files in the right folder, as you are supposed to do. However, whenever I try to play the songs my keyboard tells me there are no files on the SD card. I've tried downloading midi files from several different sites, but it still won't work. Anyone knows why this is happening? And how I could fix it?