The curtains are dark in the mirror image, as they were the original object but not receiving the light of a point lamp that i used nodes to define color and strength (blackbody and ies texture). The mirror shader i got from one answer here to "realistic mirror", but the result is the same when I use a simple glossy bdsf, GGX (or others), white (RGB=0.8,0.8,0.8), roughness=0.000. The other problem is that the translucent light that comes from the window is different too...using "realistic mirror" it is brighter, and the simple glossy it becomes green! (I'm using cycles, an HDRI map for world and a point lamp)
Yes, the problem isn't the mirror material (since I still have a problem, with a simple glossy bdsf linked to material. But the curtains material, I got from some youtube tutorial, it has a light path node, wich controls the fac of a mix shader. When i cut the link between add node and the fac mix shader the mirror works fine. I dont have enough light in the scene because i didnt included all the lamps i'll need...i had this problem first. The mirror base color is pure...at least when i use the simple glossy shader.