CANT VOTE!!

please help me I cant vote on the chat box i voted last wednesday november 17 but when i check out the website everyday the voteing panel doesn't come back.. then I notice this on the top of the page "Warning: date() [function.date]: 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 'UTC' for '8.0/no DST' instead in C:\xampp\htdocs\vote\class\class.vote.php " I hope someone can help me thanks...