I've had this problem a few times on different computers and it's always something different. Sometimes the FW works but the USB doesn't. Sometimes it's reversed. If the FW isn't plugged in exactly right, it won't work either. I originally had to update the firmware when I first got it or nothing worked. Sometimes it will error out in the middle of a transfer if I'm doing other things on my computer. I just keep trying different things until I can get it to transfer.