It seems to be a bug.
Back up all data, then move the iPhoto library to the Shared folder.
If you have more than one user account, you must be logged in as an administrator to carry out these instructions.
Select the text on the line below by dragging across it. Don't include the blank space at the end of the line. Only the text should be highlighted.
sudo chmod -R +a "staff allow list,add_file,search,add_subdirectory,delete_child,readattr,writeattr,readextattr,writeextattr,readsecurity,file_inherit,directory_inherit"
Copy the selected text to the Clipboard by pressing the key combination command-C.
Launch the Terminal application in any of the following ways:
☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)
☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.
☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.
Paste into the Terminal window (command-V), then press the space bar.
Now switch to the Finder and and select the iPhoto library. Drag into the Terminal window. More text will be added to what you entered.
Click in the Terminal window to activate it, then press return.
You'll be prompted for your login password, which won't be displayed when you type it. You may get a one-time warning not to screw up. You don't need to post the warning. If you don’t have a login password, you’ll need to set one before you can run the command. If you see a message that your username "is not in the sudoers file," then you're not logged in as an administrator.
The command may take a noticeable amount of time to run. Wait for a new line ending in a dollar sign ($) to appear. You can then quit Terminal.
