Selective Edit Tool not working

Hello! I just bought the premium version of Lightroom. All of my tools seem to be working except my selective edit tool. When I use the healing brush, it works like a charm, but I head over to the selective editing tool and nothing happens. It doesn't let me do a thing. Please help! I'm really excited to be able to edit my photos from my new camera! 

Also, I don't know if this is helpful, but I have a Google Chromebook