Plesk 11.x / Windows :: Script PHP For Creating Subdomain

I am trying to write a script PHP creating a subdomain on a server when executed (as well as doing other stuff, but that part work). But, when I send my request to the server, the script, while it does create the subdomain, doesn't display anything upon execution (I have put a few echo in the script to check the advancement, and nothing appears).

The error message : Echec du chargement de la page Aucune donnée reçue.

Here is my code :

/**
* Returns DOM object representing request for creation of new subdomain named after the parameter
* @return DOMDocument
*/
function createSubdomain($nom)
{
$xmldoc = new DomDocument('1.0', 'UTF-8');
$xmldoc->formatOutput = true;
$packet = $xmldoc->createElement('packet');

[Code] ....

The function curlInit and sendRequest are those used in the examples provided on this site, but I put them here just in case :

/**
* Prepares CURL to perform Plesk API request
* @return resource
*/
function curlInit($host, $login, $password)

[Code] ....

Why it doesn't send anything back ? When I modify the property line in the request, the script displays something, but it also fails at creating the subdomain (because the parameters are incorrect).