Post Data to server by WinHttp

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C++

Hi,
I am trying post some data to one php server that accept data by "POST" method.
I am using below standard code that I found in MSDN.
My server address is: www.arad.com//up/up.php
Data want Post is: "/MT4i TradeCopy Sender MT4iTradeCopy 2013-10-11"

And my code is:

#include "StdAfx.h"

#include <windows.h>
#include <tchar.h>
#include <stdio.h>

#include "winhttp.h"
#pragma comment (lib,"Winhttp.lib")
int main(int argc, char *argv[])
{
	LPCWSTR server=L"www.arad.com";
	LPCWSTR ext=L"/up/up.php";
	LPCWSTR data=L"/MT4i TradeCopy Sender MT4iTradeCopy 2013-10-11";

	BOOL  bResults = FALSE;
	HINTERNET hSession = NULL,
		hConnect = NULL,
		hRequest = NULL;

	// Use WinHttpOpen to obtain a session handle.
	hSession = WinHttpOpen(  L"A WinHTTP Example Program/1.0", 
		WINHTTP_ACCESS_TYPE_DEFAULT_PROXY,
		WINHTTP_NO_PROXY_NAME, 
		WINHTTP_NO_PROXY_BYPASS, 0);

	// Specify an HTTP server.
	if (hSession)
		hConnect = WinHttpConnect( hSession, server,
		INTERNET_DEFAULT_HTTP_PORT, 0);

	// Create an HTTP Request handle.
	if (hConnect)
		hRequest = WinHttpOpenRequest( hConnect, L"POST", 
		0, 
		ext, WINHTTP_NO_REFERER, 
		WINHTTP_DEFAULT_ACCEPT_TYPES,
		0);

	// Send a Request.
	if (hRequest) 
		bResults = WinHttpSendRequest( hRequest, 
		//WINHTTP_NO_ADDITIONAL_HEADERS,
		WINHTTP_NO_ADDITIONAL_HEADERS,
		0, (LPVOID)data, wcslen(data), 
		wcslen(data), 0);

	// PLACE ADDITIONAL CODE HERE.

	// Report any errors.
	if (!bResults)
		printf( "Error %d has occurred.\n", GetLastError());

	// Close any open handles.
	if (hRequest) WinHttpCloseHandle(hRequest);
	if (hConnect) WinHttpCloseHandle(hConnect);
	if (hSession) WinHttpCloseHandle(hSession);


	return 0;
}

But hen try POST, it send nothing to server. How can I fix that?
Another question:
What is max length for data that can Post to server?
Regards,