Navision failure after instream

After processing the following code Navision finishes operation.

Varibales

WinHttpRequest : Automation : Microsoft WinHTTP Services, version 5.1'.WinHttpRequest

soaprequest : Text 1024
Textvar : Text 1024
ResponseFile : File

soaprequest:='"<?xml version=\"1.0\" ?><soapenv:Envelope' +
' xmlns:soapenv=\"http://schemas.xmlsoap.org/soap/envelope/\"' +
' xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\&quot;
><soapenv:Body><ans:pull' +
' xmlns:ans=\"http://xxxx.com//\"' +
'><Username>xxxxxx</Username>' +
'<Password>xxxxxx</Password>
</ans:pull></soapenv:Body></soapenv:Envelope>"';

IF ISCLEAR(WinHttpRequest) THEN
CREATE(WinHttpRequest);

WinHttpRequest.Open('POST','https://xxxxxxxx', FALSE);
WinHttpRequest.SetRequestHeader('SOAPAction', 'true');
WinHttpRequest.SetRequestHeader('Content-Type', 'text/xml');
WinHttpRequest.SetClientCertificate(xxxxxxx);
WinHttpRequest.Send(soaprequest);

ResponseFile.TEXTMODE(TRUE);
IF NOT EXISTS('D:\test.txt') THEN
ResponseFile.CREATE('D:\test.txt');
ResponseFile.CREATEINSTREAM(WinHttpRequest.ResponseStream);
ResponseFile.CLOSE;


An empty file is generated. What's wrong??