View DXFs in Windchill

I create a DXF file from my Pro/E and save it into my workspace. It allows me to upload and check in. This allows me to view it in my AutoCAD workgroup manager, but I have no way to open it in AutoCAD. It acts like it doesn't recognize the file type and what program to use to open it. How do I link my DXF files so they can be opened in AutoCAD?