3DS max cannot export properly."Sub-Material is not standard type. Skipping Mesh."

I’m trying to make a Corvo Attano mod that replaces Ellis in L4D2 but when I try to export him as an .SMD, I just the error: “Sub-Material is not standard type. Skipping Mesh.” Which means only the bones get exported. I’m using 3DS Max 2012 Studio if that helps. Since I’m inexperienced with 3DS Max, chances are I’ll have no idea what you’re talking about. We could do Team Viewer if that’s okay with you, thank you for all your help!