I think I have found the problem. Not with your software, but my lack of knowledge of how the programs work.
I have worked before with Airport Design Editor, and when I looked at the ORD AFCAD, I noticed ( and should have known ) that some gates have small parking radii, and can't handle the 737, for example.
I haven't yet found the minimum parking radius for the 737, but when I do I will avoid the gates with a small radius.
Sorry for the trouble I have caused.
Dave Hinson