Hi I'm trying to make textures to sell, and I want to post screen shots so obviously I put them in my customs folder (This is a bicep texture), an I label it l_biceps. It's saved as a TGA file, RLE compression, and Auto-Detect (I'm using Paint.net for this).

When I save it in my customs folder, it won't show it in my single player mode, which is where I want to view it.

Remove RLE compression, and it should work. Another tip is to make a new custom folder, so that the textures aren't deleted every time you play MP.

or right the custom folder, properties then you tick "READ ONLY" then done

your item file wont accept textures for items that u dont hav so use ukes folder instead