Hi John.

I know I am a couple of years but this might help some other people. Save the CAD file as extension IGES and import it to DesignModeller. When you generate it under '0 Parts, 0 Body' in DesignModeller, you should get a certain # of Parts and Body for each distinct part. If that doesn't work, you can try uninstalling the software and installing it again, and following the same steps above.

Hope this helps.