I am struggling to relocate pins in iPhoto.

I have checked here and in help but following the directions I cannot always make the pin turn yellow by clicking it. Sometimes it works but not always what am I doing wrong?

I can still drag the red pin but it it reverts to it's oringinal location when I close the photo thumbnail.

iPhoto>Photo's>highlight thumbnail of photo to move>click i "info" button at bottom of right pain (sic)>click red pin, sursor changes from pointer to hand(?)>should turn yellow? Doesn't :-(