Remove Xanatons antennae that you previously had in your game they are probably in conflict.
As for recoloring his file, this is what he himself has to say about that: "You have to change the in-package textures. But as accessories are not like objects, you have to create a new "extension" package for the mesh and link this to it, thus it's not really just a "recolor"."
With these new files in the Antennae Mesh download, that isn't necessary. You can recolor it easily with bodyshop in to any color you like and it will automatically show up in the game thanks to HP.
Why the skins from
http://www.insimenator.org/showthread.php?t=77358 doesn't show up, that puzzles me.