Failed to open file:Could not load dxf.

Hey all, first time user here.  When I try to import contours from a dxf file, I get the following error: "Failed to open file:Could not load dxf". I've tried dxfs formatted for various versions of AutoCAD.  I get the same error each time.

If it helps come up with ideas, I'm also unable to paste contours directly into Kubla Cubed from AutoCAD or MicroStation.

Any advice would be helpful.

Thanks.