Pictures aren't showing up when I try to upload them?

Okay, so, I was trying to tineye a photo to find out the original source, but when I clicked browse on my Mac, it gave me a bunch of exclamation points.
I know that it means that there isn’t a picture there, but when I go to iPhoto, there are none of the exclamation point things in sight.
How can I get rid of the exclamation point pictures?