set language error

[dashan]

when i setup the language to chinese_china , error:

Fatal error: Uncaught exception 'Exception' with message 'DateTime::__construct() [<a href='datetime.--construct'>datetime.--construct</a>]: It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected 'Asia/Chongqing' for 'CST/8.0/no DST' instead' in /var/www/ispcp/gui/admin/multilanguage.php:204 Stack trace: #0 /var/www/ispcp/gui/admin/multilanguage.php(204): DateTime->__construct('201002271600') #1 /var/www/ispcp/gui/admin/multilanguage.php(260): show_lang(Object(pTemplate), Object(Database)) #2 {main} thrown in /var/www/ispcp/gui/admin/multilanguage.php on line 204

why ?