How do you edit Lightroom 4 photos in PSE 11?
In Lightroom, right-click on a photo, select Edit In... and then select Photoshop Elements
If Photoshop Elements is not listed, you have to configure Lightroom under Edit->Preferences->External Editing
I have entered PSE in my preferences. The issue is that the photo does not appear in PSE when it opens.
Please read this thread, I believe the answer is in reply #4