well ... here are some images for comparison. a torus, with a dielectric material assigned to it and a spot-light which casts the light. and for comparison the same scene again rendered with brazil ... and there you can see those transparent shadows which i would like to achieve with mental-ray too:

mr dielectric-material: https://www.subbz2k.com/misc/torus_mr.jpg
brazil glass-material: https://www.subbz2k.com/misc/torus_brazil.jpg

these 2 images are all rendered in the same conditions within 3ds max. i reduced the overall quality to improve the render speed but the differences should be seen. with the brazil rendering you can see those transparent shadows which are generated by a simulated area-light. notice that they are generated within the surface too (what a beatiful natural behavior ). in the mental-ray rendering you see a sharp edged raytrace shadow (because within 3ds max i have to change the light-source to generate area-lights with mental-ray but this is incompatible with brazil so i left off) but the important thing is the absolutely black shadow: that's not correct.

so again: can somebody tell me, how to get those transparent shadows with the dielectric material as shown in the rendering from brazil ??

plz help i'm out of ideas