Launching a particle effect in the camera direction

I have a fixed vector, (-0.8f, -0.8f, 6), i want to make the particle effect go in the cameras direction with a velocity. I tried using setInitalVelocity in the update method when click is pressed, but the particles just go around in random directions, even though i set it to cam.getDirection().mult(10). Any help is appreciated.

Make sure the velocity variation is 0