I'm in the process of creating an Episode 2 (Orange Box Build) mod but I appear to be missing the particle effects that the build grants. Particles such as the blood "splat" effects, hunter flechette explosion and the dripping blood.

I've got the particles folder in from the Episode 2 gcf in my mod folder, however that hasn't helped, and I'm not sure what other things could be causing the lack of particles/effects.
Everything else Episode 2 related seems to be fine. (HUD, new NPCs, Skins etc.)

Does anybody know what the problem could be, or what I could be missing?
Thanks very much.