Animating a Curve to Interact with Particles

So I’m stuck here, I’ve been trying to animate a curve through the Build modifier but it’s just not interacting with the particles. Here is the effect I want to achieve:

/uploads/default/original/4X/9/1/4/914d7fa846ebb7a2f863d2783bf48c710fa3fd53.jpgd=1406507988

Blend File: https://www.dropbox.com/s/ypz1e94o4dvnjbd/Test%202.blend.