DWG reference file not visible

Question:

I'm trying to import a 3D DWG file to Tekla Structures, but all I get is empty graphics, even when I see the DWG file on the reference file list. 

Answer: 

If you insert the DWG file through File - Insert Reference Model, and it shows up in the Reference Model list but there is nothing showing up in the model, check if the file contains proxy objects. Proxy objects should be removed from the file to make the file viewable in Tekla Structures.

Proxy objects are supplemental representations of the original intelligent objects from AutoCAD add-on applications. The proxy information is retained in the DWG even if you save it in an earlier DWG version. There is more than one way for removing the proxy objects in AutoCAD:

1. Load the original application or "object enabler" for the proxy objects and remove them with AutoCAD.
2. Explode the intelligent objects to standard AutoCAD entities before saving in the original application. 
3. Save the data to DXF format in AutoCAD. You will need to use command DXFOUT and save as R12 DXF version, this will remove proxy object information. You can then either save the file in DWG format, or import the DXF directly to Tekla Structures. There are also applications that are designed for removing proxy objects from CAD files.