How to use CreateMenu and AppendMenu

I'm trying to write a simple hook (a harmless one, though).

Code:

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

int main(){
	HWND hwnd;
	HMENU menu;
	HMENU subMenu;
	
	hwnd = FindWindow("Notepad","Untitled - Notepad");
	
	if (!hwnd) {
		printf("Notepad is not running yet!!\n");
		exit(0);
	}
	else {
		ShowWindow(hwnd,SW_SHOWNORMAL);
		SetForegroundWindow(hwnd);
		menu = GetMenu(hwnd);
		subMenu = CreateMenu();
		AppendMenu(subMenu, MF_STRING | MF_POPUP, 100, "Bar");
		AppendMenu(menu, MF_STRING, (UINT)subMenu, "Foo");
	}	
	return 0;
}

The code manages to append the menu "Foo" to notepad.
Unfortunately, the "Bar" submenu (under "Foo") is not shown.
What's wrong here?