Code:
function playMusic() {
		if (event_type ==EVENT_SCAN && you==player) {								//The Player entity has scanned me
			if (media_playing(nMusicHandle) == 0) {									//Only play me if there is no music
				nMusicHandle = media_play(sMusicTitle, NULL, nMusicVol);
			}
			else {
				showDialog("Music Handler in use.");									//DEBUG CONDITION
			}
		}
   }



It is supposed to start the function as soon as the player scans the object. If already a track is playing (handler > 0), none should be played. Actually it starts the track over and over again, playing it in dissonance as long as the player scans the object.

I can only imagine I use the condition wrong, but that's what I ttok from the manual.