Hi
It might be a bug in Joomla 1.6.3 or something special with your site. The solution is :
1. Maybe you should upgrade your site to latest version of Joomla (Joomla 1.7.1 will be released in the next few days) .
2. Edit the language file directly using a text editor. The language file is located at language/en-GB/en-GB.com_eventbooking.ini
Hope this help !
BTW, I will move this post to General Discussion forum !
Tuan