Weird Optimization Problem?

[GavG]

When I exported my station to my newest coaster Termite, there was a weird problem with some of the faces.

NOTE: I didn't do anything to optimize the 3ds, I just made it and used anim8tor to fix the color problem.

Here are the stairs...

Here is the through the station hole
(You Can't see the other side of the Station

And then the other side of the fly through you see in the second picture (problem is reversed)


If anyone could tell me how to fix it I would appreciate it.
Thank You.

Although I have never used Anim8tor, I'm assuming you don't have any "Material" on the inside of the station, so when you see through it's as if there was a 2 way mirror. -Just a guess-

Problem solved thanks to hazbruv.