How to fix error C3861: 'ChangeLanguage': identifier not found

[SdHuma45]

Hello all,

I made a windows form with a combo-box and a label in VC++ 2010. I have added three resource files one English (default), second French and third Spanish by changing localizable property of the form.

Example: Named label as 'Hello' (default), and 'Halo', 'Bonjour' in respective languages. In combo-box I added three items: English, French, Spanish.

I need to display that label when a particular language is selected. Here is my code:

#pragma once
#include"stdAfx.h"

namespace locale_check {

	using namespace System;
	using namespace System::ComponentModel;
	using namespace System::Collections;
	using namespace System::Windows::Forms;
	using namespace System::Data;
	using namespace System::Drawing;
.
.
.
private: System::Void Form1_Load(System::Object^  sender, System::EventArgs^  e) {

            comboBox1->SelectedIndex = 0;
			 }
	private: System::Void label1_Click(System::Object^  sender, System::EventArgs^  e) {
			 }
	private: System::Void comboBox1_SelectedIndexChanged(System::Object^  sender, System::EventArgs^  e) {

				 if (comboBox1->SelectedItem->ToString() == "English")
            {
                ChangeLanguage("en");
            }
            else if (comboBox1->SelectedItem->ToString() == "French")
            {
                ChangeLanguage("fr-FR");
            }
            else
            {
                ChangeLanguage("sp");
            }
			 }

When I run the code i am getting error named as:
error C3861: 'ChangeLanguage': identifier not found.

Please, help me get through this error. And how to display that language's label in the output upon selection in combo-box?

Thanks.