If you are trying to use the ones from KingTigers pack you will need to rename it so the sim will recognize it . If you are running the newest version of SB I dont think those skins are compatable with the new Leo model. These skins are for versions prior to 2.46 Directly from the download info, "This is a request, its my old strv121 with MekB10 marking. Both in DDS and BMP. use DDS for BETA version and BMP for normal SBP".