Just got a new SDJ-2 in the mail yesterday. Plugged it in this morning, took several different SD cards and tried them out in the unit - doesn't seem to be recognizing any of them. First one was a 4Gb SDHC card with multiple folders - each containing MP3's. Second one was a 2Gb SD card with multiple folders. Third one was the 1Gb SD card that came with the unit - no folders, just MP3's on it. Not one of these 3 cards seemed to be recognized. Any ideas for help???