Back to Arrangement button

I still cannot get a feel for the red button that pops up and greys out my screen. As shown in tut#2 and in Tut# 19 of the Core Live 8 videos. I tried to do exactly what was done in the video #2. I set my markers and mapped them to the numbers on my computer kybd. BUT, when I hit a marker the red button lights the screen greys out and I hear nothing. What step am I missing ??