Trouble with Sublogic Flight Assignment: ATP's USA Scenery on DOS Emulator

Hello,

I am using a DOS emulator (DOSbox) to run the old ATP airline flight simulator on this Windows PC.  All the functions are working just fine.  However, when I try to add the USA East or West scenery, the scenery becomes basically blank, just land and sky showing, no airports or details.  I have not been able to figure out where the problem comes from.  It seems familiar from many years ago and there was some solution, but I have researched around the internet and not found anything.

Is anyone running ATP with the USA scenery packs, and do you know this problem I have?

Thanks!
Kurt