I've been trying to add cubemaps to my map arena_skyline, but whenver I try to construct it I run into a problem. I get the following error message, and nothing happens. Current mod isn't in a subdirectory of "game"! *** Error: Skybox vtf files for sky_gravel_01 weren't compiled with the same size texture and/or same flags! Can't load skybox file sky_gravel_01 to build the default cubemap! Can anyone help me understand what this means, and how I can fix it?