REST CALL API in PHP

Hi, I've a problem with a call to the API for report generation in PHP.

$curl = curl_init();

curl_setopt($curl, CURLOPT_URL, "http://xxx.xxx.xxx.xxx/vCenter-CB/api/report?version=2.5");

curl_setopt($curl, CURLOPT_PORT , 8080);

curl_setopt($curl, CURLOPT_HTTPHEADER, array('Accept: application/xml'));

curl_setopt($curl, CURLOPT_HEADER, true);

curl_setopt($curl, CURLOPT_POST, true);

curl_setopt($curl, CURLOPT_VERBOSE, false);

curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

curl_setopt($curl, CURLOPT_USERAGENT, "Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)");

curl_setopt($curl, CURLOPT_TIMEOUT, 60);

curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, 60);

curl_setopt($curl, CURLOPT_POSTFIELDS,     $chiamata);

curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);

curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);

curl_setopt($curl, CURLOPT_COOKIE, $cookie);

$response = curl_exec($curl); 

The body passed seems correct :

<?xml version="1.0" encoding="UTF-8"?>

<Request>

<Reports>

<Report>

<MetaData>

<Name>SampleReport</Name>

<Description />

<ReportType>COST_REPORT</ReportType>

<OwnedByName />

<ReportPeriod>

<From>1</From>

<To>9999999999999</To>

</ReportPeriod>

<Hierarchies>

<Hierarchy id="132665">

<Entities>

<Entity id="132666" costModelId="931" />

</Entities>

</Hierarchy>

</Hierarchies>

<ComputingResources>

<ComputingResource id="1" />

<ComputingResource id="2" />

<ComputingResource id="5" />

<ComputingResource id="6" />

<ComputingResource id="9" />

<ComputingResource id="10" />

</ComputingResources>

</MetaData>

<Configuration>

<Computation>

<Settings type="costVariance">

<Property name="enabled" value="true" />

<Property name="granularity" value="DAILY" />

</Settings>

</Computation>

</Configuration>

</Report>

</Reports>

</Request>

Using a Rest client , it work with a corrent resonse.

USing this method I receive a 200 OK for the call but the API give me this response :

<?xml version="1.0" encoding="UTF-8"?>

<Response xmlns="http://www.vmware.com/vcenter/chargeback/2.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" status="failure">

  <Error majorErrorCode="500" minorErrorCode="0" message="No such method defined or API call missing required arguments." />

</Response>

any suggestion ?

thanks