Mac re-install, Adobe camera-raw no longer automatic

I use iPhoto to extract the photos from my camera and to organise them.
Until I wiped and re-installed my Mac, I could double click a RAW image
in iPhoto and ACR would fire up and allow me to manipulate the image.
Now, however, despite choosing PS as the external app to use for photo
manipulation, only PS starts but the photo is not opened.

Any ideas?