sprite editor will not apply selections.

I have watched a couple tutorials which seem to be a very simple process to create several sprites from one image. the tutorials seem to show its as simple as putting a png image into the assets folder, changing the texture type to "sprite" and "multiple". then I open the editor and make sprite selections and push apply. when I close the editor it says "changes not applied would you like to save?". I click yes and still get nothing. I cant get my image chopped up. I am using a 512x512 png image. is there some step im missing?