CONFIG4 wrote:
Had this problem with a macbook pro retina and tried everything suggested (including PRAM reset) in this forum but nothing fixed the issue. However, after we changed DNS server in Network Settings from using the router address for DNS (in our case 192.168.1.1) to any other public DNS server (verizon at 4.2.2.2, google at 8.8.8.8, etc), iPhoto sharing features immediately started working again. Hope this helps!
This was the fix for me running iPhoto '11 (9.4.3). I had Google's public DNS servers (8.8.8.8 and 8.8.4.4) specifically set on our WiFi router AND on our MacBook Pro running Mtn Lion. Realizing this was a bit redundant, I removed the manually set DNS servers from OS X and relaunched iPhoto and that fixed my issue.
I had previously tested other theories such as bad preferences by opening iPhoto in a Guest account and even resetting the PRAM (which seemed silly but easy enough to try).
Nothing worked except for the DNS adjustment.