Cannot save images back to Lightroom

Hi,

I have just updated both Lightroom and Photoshop to the latest version...

When i open a image (edit) in Photoshop from Lightroom, Photoshop does not let me save the file back. I always get the warning that the filename does not exist. Any ideas ?

I am using nikon *.nef files in lightroom than edit in Photoshop (a process that worked fine for the last 3 years....)

Thx,

Thomas