What type of operating system is your server running? (Linux, Windows) What version of MySQL do you have osTicket installed on? What version of PHP do you have osTicket installed on?
Do you have error reporting enabled? To enable error reporting:
Open file /main.inc.php and find
ini_set('display_errors',0);
ini_set('display_startup_errors',0);
Edit that to
ini_set('display_errors',1);
ini_set('display_startup_errors',1);