neophil78; what version of WB are you using, in 7 there is now a check box for textures for explorer backgrounds; Settings, Advanced settings (uis2/1 only). If that is checked not sure why you can't use backgrounds, there is no setting in SkinStudio that would tell a skin not to.
Latest version of WB. Of course i can use Backgrounds Explorer & Texture with WB skins, but it's not (and it has never been) working with Camouflage WB (under XP and with the substyle Camouflage for XP). That's why i'm asking, there's something in the .uis file (i believe) which is not correct (i noticed lots of vista's specifics, but as i don't get vista i'm not sure it comes from there ...)