Purchase multiple tickets page hangs - by: azurelink

I have Events Booking 2.1.0 running in a Joomla 2.5.28 site.
When I am in an event's Detail page and I click on the "Purchase Multiple Tickets" button and next specify the number of registrants and I click the "Next" button, the spinning loading icon displays and just keeps spinning. I am not redirected to the next screen.

What could be the problem?

Thanks!