Outdated RSS code? "This XML file does not appear to have any style information associated with it."

Question

I am creating an RSS feed that pulls both "Trains" and "Vintage Cars" from a database. When I run the code it reads, "This XML file does not appear to have any style information associated with it." Any advice would be helpful, thanks!

<?php

$dbc = mysqli_connect('localhost', 'USER', 'PW', 'DB')
    or die('Error Connecting');

header('Content-type: text/xml');
echo '<?xml version="1.0" encoding="UTF-8"?>';

$builddate = gmdate(DATE_RSS, time());
?>

<rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom">
<channel>
    <title>Vintage Cars</title>
    <atom:link href="http://<?= $_SERVER['HTTP_HOST'].$_SERVER['PHP_SELF']; ?>" rel="self" type="application/rss+xml" />
    <link>http://localhost:8888/L9/index.php</link>
    <description>Vintage Cars - Lesson 9</description>
    <lastBuildDate><?= $builddate; ?></lastBuildDate>
    <language>en-us</language>

<?php

    $query = " SELECT * FROM products WHERE productLine = 'Vintage Cars', 'Trains' ORDER BY dateAdded DESC LIMIT 10 ";
    $result = mysqli_query($dbc, $query)
 or die("Error querying database => $query");

//Loop through and print data
while ($newArray = mysqli_fetch_array($result)) {
    $product_code = $newArray['productCode'];
    $name = $newArray['productName'];
    $product_line = $newArray['productLine'];
    $scale = $newArray['productScale'];
    $vendor = $newArray['productVendor'];
    $description = $newArray['productDescription'];
    $buy_price = $newArray['buyPrice'];
}


?>

<item>
    <title><?php echo $product_code - $name; ?></title>
    <description><?php echo $description; ?></description>
    <link>localhost:8888/L9/product.php?pid=<?= $product_code; ?></link>
    <guid isPermaLink="false">localhost:8888/L9/product.php?pid=<?= $product_code; ?></guid>
    <pubDate><?php echo $pubdate; ?></pubDate>
</item>


</channel>
</rss>