HaloMods "Classic" Read-only Archive

I'm new to the whole 3ds thing, but anyway, I was watching the HEK tutorial (the second video) for the ropes. Anyway, it got to the part where I have to choose the "face" tool, go into surface properties, and choose "flip". When the tutorial presses the flip button, the level faces inward, but when I do it, my box just turns all black, and I can't see my map when I do put it in there.

Whats the deal? How can I fix it?

Thanks,
Coz

That's happens for me to but scroll so you are inside the box
or hide the roof and two walls