SOAP（PHP）基本构造错误

Question

I am trying to create a connection to a SOAP client. It works just fine on one server (running PHP 5.3) but it fails on the other one that uses PHP 5.2

Here is my code:

$url = "https://secure.pay-read.se/PostAPI_V1/services/PublicPayerCore?wsdl";
$client = new SoapClient($url);

Pretty basic stuff, but I get the following exception on the latter server:

SOAP-ERROR: Parsing WSDL: Couldn't load from 'https://secure.pay-read.se/PostAPI_V1    /services/PublicPayerCore?wsdl' : failed to load external entity https://secure.pay-read.se    /PostAPI_V1/services/PublicPayerCore?wsdl

I have checked the phpinfo() file on the troublesome server and SOAP is enabled. So is OpenSSL. This could be a server error, I would like to contact the webmasters to check with them but I am not really sure what to ask. My technical jargon is very limited when it comes to the SOAP architecture.

Are there any known issues with SOAP and PHP 5.17 (5.2)?

Thanks.