Why are some photos not appearing in events?

My Mac Pro has iphoto 11 (latest software) and iTunes 11 (latest software). 2 issues I could do with some help with:

1) When I view photos via my Apple TV2 not all the pictures in an event appear. I think this has been a problem before but is particularly obvious today as I have an brand new event containing 3,711 pictures from different sources (SD card, iPhone and iPad) but only 3,518 are visible. The photos that are missing are not the biggest photos or the smallest photos and I have examples from all the sources mentioned above. Most of my photos are edited in one way or another.

2) The photos in the event are also not in the same order at those in the Event on the Mac. I have changed the dates/times on the original pictures on the Mac to get the pictures into order so it will become very frustrating when trying to give a slide show in a specific order!

Any help gratefully received.