Engaging saved loops during playback

Hey Guys

Just got my DDJ-S1 and love it so far. The only thing i'm still trying to figure out is how to engage a pre-set loop during play. For example, if I want to engage a loop that is coming up during a break down, I can select the loop (light green) but how do I enable it so it will loop when it reaches that point?

If I hit the RELOOP BUTTON it just loops it from the start of the loop. Is there anyway to turn on/off the preset loops as they arrive in the song?

MZ