PHP 中未终止的实体引用

这是我的代码：

<?php
// 27/01/2016 Edit:
$result = mysql_query("A Long mysql query");
$rss = new SimpleXMLElement('<rss version="2.0" />');
$products = $rss->addChild('products');
///
while($row = mysql_fetch_array($result)){
$product = $products->addChild('category');
$product->addChild('product_id',"$row[product_id]");
$product->addChild('cat_id',"$row[cat_id]");
$product->addChild('cat_name',"$row[cat_name]");
$product->addchild('product_code',"$row[product_code]");
$product->addchild('product_name',"$row[product_name]");
$product->addChild('description','$row[description]');
$product->addchild('rating',"$row[rating]");
$product->addchild('image_url','$row[imag_url]');
$product->addchild('price',"$row[price]");
$product->addchild('discount',"$row[discount]");
$product->addchild('stock_status',"$row[stock_status]");
$product->addchild('stock_quantity',"$row[stock_quantity]");
$product->addchild('weight',"$row[weight]");
$product->addchild('length',"$row[length]");
$product->addchild('width',"$row[width]");
$product->addchild('height',"$row[height]");
$product->addchild('colour',"$row[colour]");
$product->addchild('size',"$row[size]");
$product->addchild('material',"$row[material]");
$product->addchild('pattern',"$row[pattern]");
};

Header('Content-type: text/xml');
print($rss->asXML());
?>

这是错误：

警告：SimpleXMLElement::addChild() [simplexmlelement.addchild]：第 40 行 C:\wamp\www\rabwah\core.php 中未终止的实体引用 _Coke.jpg

错误在于'$row[imag_url]'.

这正确编码了& < > and "" ''

$parent->addChild($name, htmlspecialchars($value));