Is your Photoshop CS6 Extended 3D feature working. Photoshop CS6 is also no 3ds max or blender. I can believe that not all their features are supported by Photoshop 3D support and some of their file formats may not be supported by CS6. What file type did you export from the 3D applications and try to open in CS6?.
How do i check if the 3d feature is working? and i used a .3ds file
The 3D feature is working if you have a 3D menu in CS6 extended and you can create 3D layers.
Photoshop supported file formats Photoshop Help | Supported file formats
I do not see a .3ds listed.
3D Studio (import only)
Flash 3D* (export only)
JPS* (JPEG Stereo)
KMZ (Google Earth 4)
MPO* (Multi-Picture format)
Isnt .3DS the 3D Studio file?????