I've been trying to this error, but no use. Call to a member function bind_param() on boolean in. Here's my code:

$stmt = $db->prepare("INSERT INTO visitors
        set page = ?,
        ip_address = ?,
        host = ?,
        browser = ?
");
//print $db->error;
$browser = $this->getBrowser();
$host = gethostname();
$stmt->bind_param("ssss", 
        $_SERVER['REQUEST_URI'],
        $_SERVER['REMOTE_ADDR'],
        $host,
        $browser
);