How to render and save shadow with matte object

[jovcem]

When I make a plane to be matte the result does not show in the alpha, so if my environment is black a get black image, is there some tutorial on how to save shadow with the matte material?
Im new to fstorm and have previously used vray, so in vray the shadow also appears in the alpha, but here the alphas is white.
Thanks

[Karba]

Hi. Try to activate process alpha option in render settings.