Non-printable control characters over serial port in C++ using WriteFile - c++

Question

I am trying to write a control character (CTRL-T, which is #20 in ASCII table) to the serial port using the WriteFile() function, but apparently it does not work.
When I use putty and press CTRL+T, I receive a response over the serial port for communication with an ATI force sensor I work with. Below is a snapshot:
However, when I use the WriteFile() function in C++, I get no response from the sensor, which indicates to me that the CTRL-T command is not written to the serial port. Below is the code snippet:
// set write character to CTRL-T (#20 = 0x14)
char t = 0x14;
// write the character to the serial port
m_serialPort.Write(&t,1);
// read 14 bytes with 1000 ms timeout from the serial port
m_serialPort.Read_N(str_read,14,1000);
I have tested the functions Write and Read_N, and they work fine when I deal with printable characters.
Does anyone have any idea how to fix this?
EDIT: Here is a sample code:
// SerialTest.cpp : main project file.
#include "stdafx.h"
#include"SerialCommHelper.h"
#include <windows.h>
#include <iostream>
using namespace System;
CSerialCommHelper m_serialPort;
int main()
{
std::string comPort = "COM1";
std::string str_read;
// Open the serial Port
m_serialPort.Init(comPort,9600,0,1,8);
m_serialPort.Start();
m_serialPort.Purge();
// set write character to CTRL-T (#20 = 0x14)
char t = 0x14;
// write the character to the serial port
m_serialPort.Write(&t,1);
// read 14 bytes with 1000 ms timeout from the serial port
m_serialPort.Read_N(str_read,14,1000);
std::cout << str_read;
system("pause");
m_serialPort.Stop();
m_serialPort.UnInit();
return 0;
}