Cannot open a file by Applescript

With Photoshop CS6, I am getting an error trying to open a file. This breaks a few of my scripts which continue to work with CS5.

This code, copied almost exactly from the CS6 Applescript Reference, returns

error "Adobe Photoshop CS6 got an error: File some object wasn’t found." number -43

Passing myFilePath to Finder works perfectly fine to open the alias.

tell application "Adobe Photoshop CS6"

          set myFilePath to alias "Macintosh HD:Users:ats:Downloads:Photoshop-CS6-AppleScript-Ref.pdf"

          tell application "Finder"

  openmyFilePath

          end tell

  openmyFilePathasPDFwith options {class:PDF open options, height:pixels 100, width:pixels 200, mode:RGB, resolution:72, use antialias:true, page:1, constrain proportions:false}

end tell