Pro Sites: Checkout Page Not Working with Pay Pal

I set up Pro Sites with paypal sandbox info. I go to a free site and click on upgrade, choose the site to upgrade. I get my checkout page, everythings ok so far.

When I choose one of the levels by clicking on it, nothing happens. I'm not sure where to start to troubleshoot this.

The only thing I see that may be odd is the page is at myexample.com/pro-site-20/

I'm also running the multi-db plugin.

Thanks