error when checkout button clicked

I am planning to sell some tickets, after searching for a while, I found about this plugin and decided to add it to my wordpress site. After some early trouble with installation I finally managed to display the ticked list. But now when I try to fill in the details and click on Checkout button, I just get a blank page and then it stops.

Please help me solve this error. You can see the output yourself on this page
http://tapandesai.oo3.co/navratri-passes-goes-on-sale/

http://wordpress.org/plugins/camptix/