Hi,
Please, send a support ticket accompanied with a sample project that demonstrates the problem using our support portal.
Best Regards,Nevron Support Team
We tested again the AutoCAD Export Example and the DXF file seems fine. For example, here's the file opened in a free online DXF viewer.
During the development of the AutoCAD export we were testing with AutoCAD 2011, but the DXF files exported by Nevron Diagram should work with older versions of AutoCAD, too (AutoCAD 2007 or newer should work fine).