3DS Exporter not Solid

I used Add>>Cube to design my simple model. I used the 3DS exporter to spit out a model.

If I open it in 3D Studio 8, the model surfaces are not “solid”. Some of them are imported correctly. Others have only 2 or 3 sides there. Very strange.

Any ideas?

can you provide the blend, 3ds file and pic of the model in 3ds if you like?
I managed to get models into 3ds with no errors.

I can’t post attachments, but if you are willing to help out, PM me and I’ll send what I have.

I looked at it in more detail. The problem parts are duplicated and mirrored parts.

If I just duplicate and then use rotate to “mirror” the part, it’s okay.