i downloaded a bunch of skins, like Vader, Maul, Desann(even though the console comand works just fine), Yoda, exc., but the only one that worked was darth maul. i brought the pk3 file into the base folder, but nothing happens in game. i tried several vader skins, but only one worked and that was for MP. i want some cool skins for SP. does anyone else have this problem? and if so does anyone know how to fix it?

Do the readme files of the models/skins say that it's for SP? Most of the time models and skins are only for MP. If it's been made specifically for SP, try downloading the file again, it may have experienced a loading problem.

However, it sounds to me like they're all MP models and skins. Adding new Jaden classes in SP is an EXTREMELY hard process, (hard at least for programming newbies like me) but it can be done. I should warn you that you had better know what you're doing, though, or you could end up screwing up the file. However, if you're still interesed, there's a tutorial for adding new models/skins for Jaden in SP at www.jk2review.com)

One more thing...

If the file says the model/skin is for SP, make sure it's for JA and not JO. JO SP models are not compatible with JA SP due to player class issues.

I've written a tutorial on how to replace Jaden with custom models in the skinning forum. It isn't too hard. You can add custom NPCs as well.

Yes, Prime's excellent tutorials are also avaliable here:
http://www.map-review.com/index.php?page=tutorial_view&id=7)
http://www.map-review.com/index.php?page=tutorial_view&id=8)

JK2Review had a name change :)

(Prime, will get tutorial number 3 up as soon as I get University sorted. Sorry for the delay!)

I know for a fact that the one vader mod was for SP, i don't know about the others, but it was definitely for SP.