Can't get linkback working
 

I was trying out the linkback feature in OG5 but can't get an object to linkback from one omnigraffle file or canvas to the original. I followed the help file (below) by drawing an object, choosing Copy > As PDF, then pasting it on another canvas and in another file. When I double clicked on either, I got the osx beachball for a few seconds and then nothing happened. I wasn't taken back to the original instance of the object like I expected. Am I doing something wrong?

Here's what the OG5 text file says:
"To embed OmniGraffle content inside a single object in OmniGraffle, choose Copy As PDF from the Edit menu, then Paste normally. The objects you copied become a single image; you can double-click the object to edit the original content."

If you have an older version of OmniGraffle present on your system, then this can happen as LinkBack can get confused about which version to launch.