simplexml problem

I wrote a script to check a remote xml file for the stock state of some products.

I want to list all sizes ID having "available"=true and "appearance id"=2

the expected result should be

2
3
4
5
6

but i'm getting

38
2
3
4
5
6

where the hell does this "38" comes from ?

Here's the script:

<?php
$checkstockcolor = "2";
	$apiurl = "http://api.spreadshirt.com/api/v1/shops/266497/productTypes/175";
	$feed = simplexml_load_file($apiurl);
    $producttype = $feed->productType;
    $stockstate = $feed->stockStates->stockState;
       	foreach ($stockstate as $stock) {
    		$available = $stock->available;
    		$stockcolor = $stock->appearance[id];
    		$size = $stock->size[id];
    			// garder uniquement les résultats de la couleur présentement sélectionnée
    			if ($stockcolor == $checkstockcolor && $available == "true") {
    			echo "$size<br>";
    			}
    	}
 ?>

Thank you !