inside face of truck/ Decal-ed body

[fernBurn]

so, I am currently attempting to repaint a truck body.  i wanted to add an inside face to it. good news: i did......The only problem now is that when i put it in-game the inside face shows up (on the inside of course)  and not the outside decal body. how do i fix it?

 

[steiale]

http://sim-monsters.com/index.php?/tutorials/article/58-how-to-put-a-inside-face-on-a-body/

[fernBurn]

followed every step, but still no luck. the inside face doesn't show up in Blender or ROR.