Problem with Tutorial (Breaking Down the Secondary Parts)

I haven’t had any problem following the video tutorials until I reached Character Breakdown Part 1 - Breaking Down the Secondary Parts. With the cutter tool selected, when I try to use alt to select only the whites of the character’s eyes, the marquee option does not select anything. The alt shortcut to swap from the lasso option to the marquee option itself works, but holding alt and simply clicking inside the white of the eyeball does nothing. Can anybody offer some insight on where I’m making my mistake?

Nevermind, I figured it out. If anyone runs into the same problem, the source material didn’t convert pencil lines to brush strokes. Works fine after having done that.