How to use Volumetric Scatter Diffusion?

[morteza.cg]

I'm having trouble using the new Scatter Diffusion feature in the Arnold volume shader.
I saved a VDB file from Bifrost Aero, created an Arnold volume, and applied the volume shader to it. Everything seems to work fine, except for the Scatter Diffusion.
No matter what values I use for the scatter diffusion attributes, I see no difference in the render—it’s as if those settings aren't working anything at all.

Is there something I might be missing or a step I'm overlooking?

[lee_griggs]

Hi Morteza, here are the settings used for the standard volume docs example.

[morteza.cg]

I tried your settings, but it's still not working! the result was the same.
My VDB file was quite heavy so I attached its Bifrost scene, you can check it out yourself.

[lee_griggs]

You need to increase the volume_ray_depth. See the UI above left.

[morteza.cg]

oh shoot! I mistook that with sampling counts, my bad! 
now it works, thank you so much for your help.