Copy photos from iPhoto to my photos (in Finder) - not working!

Hi all,

I am trying to copy photos from iPhoto across to Pictures in Finder. Never had a problem before. Photos go from iPhone to iPhoto, I create an album on that, then usually copy them across - copy and paste - however now I have an album of 42 pics, but when I select all and copy across, only 22 get recognised and copied. Any reason? Help please!

Thanks