can't upload logo

I downloaded and installed this theme on Saturday, January 24, 2015 EST. Whenever I go to the customize page and try to upload a logo nothing happens. I click the upload button, choose the file I want, and click Open, and dialogue box closes but nothing’s changed. All the permissions in all the directories and files are set to 755. Is this insufficient? I was thinking maybe it’s having trouble creating a directory to upload the file into for some reason, so is there a directory that I can create and manually upload the logo using FTP instead of using the web interface?