iPhoto event will not synch to my iPad

I have tried multiple times to sync a certain event to my iPad 2 (iOS5) from my Mac Mini (Lion). The event was entered into iPhoto in September, and I have even set iTunes to synch my last 12 months worth of events, but that one event will not show and I am completely stumped.

I've restarted both units and re-sync'd. I've tried to sync this event to my iPhone also, with the same results, it will not sync.

The only thing different about this event is that I imported those photos from my girlfriend's iPhone.

Is it a permissions thing?

Thank you in advance for any advice!