At first, how did you enable them?
You don't give much information so I can only guess.
If you want to add new skins you also need to add new faces textures and naked torso/pelvis textures. Let's say you have 13 skins instead of 12, with a 0 in the column #3. Then you also need to add this entry for 1/4.
This means if you wanted to add the human male skin HumanMaleSkin00_100.blp you would first need to allow it to display for characters.
This is done in column #7 (on zero based counting)
This is a bitmask. It's not really documented on the wiki, but I think 0x1 is playable, 0x4 marks a deathknight skin, 0x8 marks an npc skin.
Currently it is set to 8 so we need to atleast set it to 9 to show up on char selection.
Now you added the skin, but the game will crash if you don't at the fitting face texture and the pelvis/torso texture.
So now you need to at a face texture (number 1 in column #3) for every face that humanmale has with it's number from line #9.
So for 12 faces you need to make 12 entries.
So you either have your own blps or use already existing. Just make sure they have the same number in #9 as you skin has.
Next you need to add the Pevis/Torso (number 4 in column #3) texture.
This is done by adding one line per new skin, since torso and skin are a single matching pair and can not be mixed like face/skin.
Just make sure that column #9 are identical as above.
I hope this helps you fixing your problem.
