Using airport extreme as repeater?

So here is a drawing of my current Wi-fi set up. I just replaced my Extreme with a Time Capsule and I wanted to see what I could do with the extreme as a repeater.





My Wi-fi max is right about where the Extreme is placed, 122 feet from the Time Capsule or 90 feet from the Express. I was hoping I could get Wi-fi to my garage by adding the Extreme. It would be so convenient to have internet out there when I'm working on my cars. The Extreme connects, turns green, and the airport utility registers it, but for some reason its not broadcasting anything so I cannot connect via Wi-fi. But if you plug in via Ethernet it works perfectly. I know I have the settings all correct so why is it not working then?