I have the node settup below, but instead of use the alpha value to make it transparent where it should be, it looks like that the light is hitting the object isnted of let the light pass trough it, Im not calculating caustics on this scene.
The result is this one down here:
Anyone knows how can I solve it?
Hmm, this is going to be hard to explain in just words. I think what you need to do is:
See if that works. I did a tutorial on this (bump, specular, diffuse map) that I listed in the tutorial section. Not sure if it’s exactly what you are looking for, but the last part of it talks about using spec maps (or you could use alpha maps) as a mask to combine two materials.
I tried that inside of the group, take a look, and I tried something like that after the grounp in order to increase the alpha cut, but I think that the problem here is that some light is hitting the alpha part that is = to zero, and cycles is calculating something there .
I dont know exactly how I can make it simply let the light pass properly…
Thanks for your reply blenderjourney
I think that this is a bug or something, I tried another method using a black and white plane and it still making that shadowing area beneath it.
If someone doesn’t get to it first, I’ll show you the nodes when I get home later this evening. Can’t do it from work 
Ok, I really aprecciate that! thanks!
Might be a bug, but imo you really need Transparent node, not Translucent. r52693. Black and white mask drawn in blender, no alpha. Two planes, close together. Could be z-fight depending on object sizes; you might experiment with distance between planes.
Ah, there you go. It’s that black/white image going into the factor of the mix shader that is the key.
You have two different shaders and where they appear on the image should be controlled by the alpha image going into the factor of the mix node.
I allready done that settup and it still not working, I deleted it all and tried again just to be shure with your settup, but look, its the same as before…
I think that this is bug or it need a more complex approach, maybe with light paths?
anyway Im still stuck, thanks for your help, I really aprecciate that!
I’ll see if I can set up an example later this evening. You could be right though. Maybe it’s just a bug.
If you need some kind of reflection texture on a wet surface that comes from ‘Glossy’ part. Then this setup needs to be a bit modified.
See if this file works as expected at least. http://www.pasteall.org/blend/17905
With your settup I have a red square with a some blue details, its not working here, Im using the latest version of blender, maybe that is the problem.
Thanks but it didnt worked too.
That’s weird. Maybe step down a version?
The final scene looks awesome 
thanks, I hope to upload the video soon, but its very slow to render un HD, so it will take a while, but thanks It means a lot!
