CHALLANGE: Weird issue scraping a retailer w/ curl PHP ...

<div id="enterZip">
<form method="post" action="/LowesStoreSearchCmd" name="storeSearchForm" id="storeSearchForm">
<fieldset>
<input type="hidden" name="URL" value="TopCategoriesDisplayView"/>
<input type="hidden" name="storeId" value="10151" />
<input type="hidden" name="catalogId" value="10051" />
<input type="hidden" name="langId" value="-1"/>
<input type="hidden" name="findStoreErrorURL" value="StoreLocatorDisplayView"/>  
<input type="hidden" name="firstReferURL" value="" />
<input type="text" name="zipCode" id="zipCode" maxlength="20" value="Enter ZIP Code"/>
<button type="submit" class="button secondary" id="submitZip"><span>Submit</span></button>  
</fieldset>
</form>

$url = 'http://www.urltostore.com/pagetoproductgoeshere';
$cookiefile = str_replace('\\','/',dirname(__FILE__)).'/cookies/somename.txt';
$zipcode = '90210';
$posturl = 'http://www.urltostore.com/LowesStoreSearchCmd';
$postfields = 'URL=TopCategoriesDisplayView&storeId=10151&catalogId=10051&langId=-1&findStoreErrorURL=StoreLocatorDisplayView&firstReferURL=&zipCode='.$zipcode;

// POST: Zip code to store
$ch = curl_init();
curl_setopt($ch, CURLOPT_COOKIEJAR, $cookiefile);
curl_setopt($ch, CURLOPT_URL,$posturl);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postfields);
ob_start();      // prevent any output
curl_exec ($ch); // execute the curl command
ob_end_clean();  // stop preventing output
curl_close ($ch);
unset($ch);

// GET HTML
$ch = curl_init();
curl_setopt($ch, CURLOPT_RETURNTRANSFER,1);
curl_setopt($ch, CURLOPT_COOKIEFILE, $cookiefile);
curl_setopt($ch, CURLOPT_URL,$url);
$html = curl_exec ($ch);
curl_close ($ch);