arrange by date

Just stumbled on a weird problem in Finder. I was looking for a picture that was taken in 2013 and added to a folder where I keep pictures of my band to deploy to our website. I arranged the folder by date added and that picture (and another from 2013) were both placed at the top of a section labeled '2012'. Clicking on each picture shows created, modified & last opened dates in 2013. I tried by date modified and by date created and they remained in 2012.