SQL error on your demo site when booking

Hi there,

I was trying to use one of your demo sites (http://rsvp.jeventsdemo.net/index.php/e ... istrations). I logged into the admin and changed the config to allow non registered users to attend/book. Then I tried to book, filled out all the required fields but when I clicked the 'Click to Attend' button, the following error displayed;

Fatal error: Call to a member function toMySQL() on a non-object in /home/jevdemo/public_html/rsvp/components/com_rsvppro/controllers/attendees.php on line 1618