Cannot connect to internet on MacBook Pro 13" Retina

Hello,

I'm trying to figure out why my brand new MacBook Pro 13" Retina will not pick up internet on my existing Airport Express.

I have multiple older mac devices on it, as well as windows machines and smart phones that do not hesitate.

I've already made sure my WiFi is set to DHCP, although I did test by inputting a static IP address. I've changed my DNS as well, but no luck.

Oddly enough, I have bootcamp with Win 8.1 Pro installed, and when I boot into Windows, WiFi works fine.

I've did a factory reset on the Airport Express, reconfigured, etc. and still no luck on the Mac Side. (10.10.3)

Thoughts? Is this a glitch between the Airport Express and the new MacBooks? The Airport Express is no more than a year old, and is on 7.6.4 firmware.

Thank you!

-Michael