I have indicated an editor preference for Photoshop Elements 10 in Aperture 3. When attempting to edit a photo located in Aperture with Photoshop Elements, the PSE editor program appears, but I cannot locate the photo in the file menu in PSE.
Likely, you are running into trouble here because of the application file you are linking Aperture to. The path has changed from previous versions of Photoshop Elements. Make sure you are pointing Aperture to the application file in this location:
//Applications/Adobe Photoshop Elements 10/Support Files/Adobe Photoshop Elements Editor