Hmmm..If your still interested. You should check your volume control panel to make sure, synthesizer isn't on mute and it up to a decent level. Your Midi output as I said should be on the internal midi emulator. You should restart the program after you change these settings. If it still doesn't work I don't know what to say. There are many other programs but this is the only free one I have found that works full-functionally and/or without warning pop-ups. Look for a program called "eartune", this one uses actually audio files (guitar) instead of midi. Good program and it's free if you can put up with the occastional pop-up.