im not sure what im doing wrong but i cant get frost to showup as a matte for a krakatoa render
ive made a selection set for it in krakatoa it says all matte objecks OK
but its not holding out anything
is there any trick that im missing?
turned depth of field on there it works hmmm
and now restarting the scene again it doesnt work…
clueless… 
i tried using the depth map file sequence option and chose the vray zdepth map (far region 1000)
/camera space zdepth get black image
/normalized zdepth i get holdout but inverted
/inverted normalized zdepth map i dont get any holdout (at default zfar 1000), when i change it to 500 this option works but still “wrong” matte (inverted)
Cannot reproduce the problem.
I created a Frost from a PRT Volume, set the Frost as matte and it occluded another PRT Volume.
Keep in mind though that if you created a PRT Volume FROM a Frost, the Frost will be set to NON-RENDERABLE in the Object Properties automatically.
This behavior is exposed in the Preferences dialog of Krakatoa and can be turned off.
Also, the Matte Objects Explorer should show you the Frost in red if ANY of the conditions for it appearing as Matte are not met.
If you are still having this problem, could you please tell us what version of 3ds Max, Krakatoa, and Frost you’re using? Also, could you please send us a scene file that reproduces this problem? (You can send us a scene file by using our ticket system.)