I'm having trouble with some skins I made

[Slimby]

In Sparkedit they look fine. But when I have it ingame the jet black parts of my skin turn semi-transparent, and the old skin shows through. This has been evident in both an Assault Rifle and Master Chief skin. Is this a common problem that can be fixed easily? Or is it an uncommon problem that will involve me remaking the skins? Thanks for any answers.

Slimby