點解我ge php5連唔到mysql5?

<?php

$conn = @new mysqli('localhost', 'root', '1228','messageboard');
$conn->query("SET NAME 'utf8'");


$fullName = $_POST["fullname"];
$userName = $_POST["username"];

$q_str = <<<EOQ
INSERT INTO users (user_id,user_name, full_name, user_email,birthday)
VALUES (110,$userName, $fullName, "[email protected]", "1900-12-03")
EOQ;

$result = @$conn->query($q_str);

?>

//thx for your help