I'm using Garageband to mix music for a four hour party. I just want to fade the songs in and out so that the music flows continuously. So each song is a different track and I've been adjusting the volume for each individual track. For example, at the end of one song, I bring the volume down while the next song is comig in. Which works fine for 20 minutes (about 500 measures), but if I try to adjust the volume of a track after that, I'm unable to move the points on the volume bar. It's like suddenly I no longer have that function. Does anyone have any idea what's going on?