how to render bifrost particle with aiStandardVolume

[BurkhardRammner]

Hi,

the title says it all.
I have bifrost points with radius and color data (properties: point_radius, color).
I wanted to get the same render as with using nParticles having rgbPP data (which works).

I took the identical aiStandardVolume from the nParticle render, changed the aiUserColorData attribute to 'color'.
Inside bifrost, I took the 'assign_material' compound node, piped the aiStandardVolume in its volume_material input and activated 'setVolume'.

What am I missing..is that possible at all?
thanks for help!

edit: converting the data via 'points_to_level_set' to a volume did not help