Opening SMDs

I’m having trouble opening SMD files in XSI mod tool 6, I’ve already downloaded the valve plugin and added it(If dragging and dropping the file into an open session of the program is how to install addons to XSI). For some reason though when I try to open SMD files they still aren’t compatible with the program, what am I doing wrong?

Sorry if there’s still a question mega thread around here, but I can’t find it anymore.