I wrestled with transmaps several times. You may need to cycle through the materials and make sure that ALL of the areas of your skirt have transarency set (and you may want to set the highlight to black). For example, sometimes a skirt has a material, a skin, a "default", etc. I've never had a solid color show up but I have had shiny spots in areas that were supposed to be transparent and double-checking these settings usually reveals the trouble. Hope this helps!