Rearranging iPhoto order - possible?

I recently backed up 12,000 pics to clear up some considerable space, and I flagged about 500 favorites from the past few years to re-import, and they are now not in time order.

I have tried to begin the laborious task of dragging them here and there to get them into the right order but this doesn't even seem to be possible.

Anything else I can try?

In iPhoto: View, Sort Photos, By Date?

Manually worked, for some reason sorting by date doesn't - I can only assume that it goes on the date last edited, not necessarily the date taken or loaded.

It will take forever, I have no idea why date order doesn't work but 500 photos taken between 2005 and now have been shaken up and jumbled together in random order. I have updated my iPhoto software but this had made no difference.

Big black mark to Apple on this one.