Particles won't fill up the entire drawing matte

I’m trying to get the particles to form into a shape, but it doesn’t quite follow the matte. They instead just form in a kind of sort of rectangular shape. Attached are some screen captures so you will see what I mean. Does anyone know what could be causing this?

I was also wondering how I can get particles to float up to make this shape?

Thank you.

There could be any number of things. Particles are kinda needy.

is your planar region set to image?
Is there any animation on the drawing
Is there animation on your peg in the left port of the particle visualizer.
Is there a mask of any kind outside the group?
Is your particle count high enough?