Motion Blur on particles stops after 12 frames

[flavrsaver]

I have a SuperSpray particle system bound to a circular path and I have motion blur enabled on my Vray Camera. Up to frame 12 the particles are blurring properly, but once I hit frame 13 the motion blur is no longer applied. I've looked through my particle settings and the camera settings, but I can't seem to figure out why the motion blur would simply stop after 12 frames. The particles continue to move around the circular path for well over 12 frames. Any thoughts as to what could be causing this?

[flavrsaver]

Also just noticed that if I change my shutter speed down to a lower number (trying to increase the motion blur) it will not render the blurring if I got below a certain shutter speed setting. For example, at a shutter speed setting of 80 I get motion blur, at 30 I don't.

[vlado]

Would be best to use particle flow for this; V-Ray does not support motion blur for other types of particles very well.

Best regards,
Vlado

[flavrsaver]

Okay, I'll try using particle flow instead. Thanks for the help Vlado.