Why can't I use a vertex group to control a particle system's density? Even with Use Modifier Stack turned on, and the Particle System being above the Subdivision Surface Modifier my Particle Systems Vertex Group Density isn't working.

I'm trying to apply a Vertex Group to the Particle Systems Density, but it seems that every time I do so, the particles seems to group up in one place and completely ignore the Vertex Group.

Example CloseUp (click to see full image):



So if anyone knows how to fix this, please let me know.
Never mind, I guess I was supposed to assign the vertex group in the particle system, while not in Edit Mode. So make sure you create a vertex group and then apply that vertex group in the density panel in the particle systems under Vertex Groups. And make also sure you aren't in Edit Mode.