The All in game textures (txd's) are linked to a model (dff). Those jeans need to be linked to the in-game jeans model. The easiest way to fix your issue is replace the starting jeans or red/green jeans.
Rename the txd to the following in your mod folder:
1. jeansdenim.txd to replace the starting jeans
2. denimsgang.txd to replace the green jeans
3. denimsred.txd to replace the red jeans
(sorry for double-posting)
that's what i did ages ago
but the problem is still there
sounds like you have another file called legs.dff which should be the underwear but you have put the jeans by accident?