First check that your DWG translator is set to the version of autocad that you are working with.
If it's not available or not working, you can use the free TRUEVIEW, a free download on the Autodesk site, to save back the dwg to an earlier version.
Better yet, ask your consultant who supplied the DWG to do it for you.
Erika
Architect, Consultant
MacBook Pro Retina, 15-inch Yosemite 2.8 GHz Intel Core i7 16 GB 1600 MHz DDR3
Mac OSX 10.11.1
AC5-18
Onuma System
"Implementing Successful Building Information Modeling"