"Make a copy" not working well

I'm having trouble making copies of the photos I uploaded since yesterday. Sometimes the copy features works, but it does randomly. It's working fine with the photos that were uploaded before yesterday, but not with the ones uploaded during the last two days.

My website is www.jonathanhoule.com

And here is a gallery containing both old photos and new ones: http://www.jonathanhoule.com/gallery/7033917_2vqn7

New photos start at photo number 55.