I can't install the Photo Lens. After running these commands:

sudo add-apt-repository ppa:scopes-packagers/ppa
sudo apt-get update && sudo apt-get install unity-lens-photo unity-scope-shotwell unity-scope-flickr

I get this:

Package unity-lens-photo is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source

E: Package 'unity-lens-photo' has no installation candidate

Is there a fix for that? Thank you very much.