Compositing troubles

[Daniele_ve]

This is my problem:

I've splitted my render into

DiffuseFilter / RawLighting / RawGI / RawReflections / RawRefraction / ReflectionFilter / Specular

When I composite them (into Nuke) all works well until I add 'Specular':

if I don't add this channel, as well if I add it, my final image is slightly different from the rendered one (also if this channel is totally black).

If I add it, but in DISABLED mode, the image is fine.

Any suggestion?
Thank's