problem with particle systems


I actually don’t think that this is a new problem. I searched around a lot, but still couldn’t find the answer though.

I’m currently working on a project where I need to produce some kind of light effects (particles) which are moving above a floor (particle grass).
Blender always seems to render my light effects underneath the grass, although they are actually above it.

I’ve tried to reproduce the problem in a smaller file, but couldn’t manage uploading… :-/

basically it’s a simple floor that’s made of particle hair and a icosphere with a halo material on it.
The halo is always shining through the grass, but I actually want it to be above it, not interacting with the grass at all.
does anyone know what I’m doing wrong?