i use photoshop cs4 to edit photos, but after editing them they still appear dark in win photo viewer, why?

Question by Elektrotechniker: i use photoshop cs4 to edit photos, but after editing them they still appear dark in win photo viewer, why?
I edited the tone and exposure of my photographs using adobe photoshop cs4, they look perfect when opened in photoshop, but when i open them in windows photo viewer they appear a little dark then they do in photoshop.

Answer:

Answer by Damien L
maybe you opened the original file, and changed the name of the one you were working on.