I cant upload a neff image from a nikon d300 to photoshop elements 6
What operating system are you using?
Do you know what version of camera raw you have?
In the pse 6 editor look under Photoshop Elements>About Plug-In>Camera Raw (mac) or Help>About Plug-In>Camera Raw. (windows)
The newest version of camera raw for photoshop elements 6 is 5.6