Normally, the "reskin" is built into the asset and that is what you see on the screen. Some assets will offer a selection of "skins" to choose from and the choice is (usually) built into the assets properties display window, these will normally be loaded with a "library" of "skins". Open up the property window of the boxcar and see what, if anything, it offers.
Otherwise, the problem may be with the asset as created.
