Sending keystrokes to other *non-focus* application

[audi02]

In order to send keystorkes or mouse clicks to other application that is not in focus, I found
in the internet the concept of using SendInput while attaching my application thread to the application I want to control. Here is the short console program code for writing the letter 'g' on the notepad program.
But still problem - it doesn't put the letter on the notepad... why?

#include "stdafx.h"
#include "conio.h"
#include "windows.h"

void sendKey(WORD wVk)
{
	INPUT input[2];

	input[0].ki.wVk = wVk;
	input[0].ki.wScan = 0;
	input[0].ki.dwFlags = 0; //press down;
	input[0].ki.time = 0;
	input[0].ki.dwExtraInfo = 0;
	input[0].type = INPUT_KEYBOARD;

	input[1].ki.wVk = wVk;
	input[1].ki.wScan = 0;
	input[1].ki.dwFlags = KEYEVENTF_KEYUP;
	input[1].ki.time = 0;
	input[1].ki.dwExtraInfo = 0;
	input[1].type = INPUT_KEYBOARD;

	SendInput(2, input, sizeof(INPUT));
}

int _tmain(int argc, _TCHAR* argv[])
{
	TCHAR	sText[1024];
	HWND	hTargetWnd;
	DWORD   processID;
	DWORD	threadID;
	
	
	HWND hNotepadWnd = FindWindow(NULL,  L"Untitled - Notepad");
    hTargetWnd=FindWindowEx(hNotepadWnd,NULL,L"Edit",NULL);
	threadID = GetWindowThreadProcessId(hTargetWnd , &processID);	
	if(hTargetWnd)
	{
		wsprintf(sText, L"Target window found\nWindow = %p\nprocessID = %x\nThreadID = %x\n",hTargetWnd,processID,threadID);
		wprintf(L"%s",sText);
		
			  if(AttachThreadInput( GetCurrentThreadId(), threadID,true))
			  {
				sendKey('G');
				AttachThreadInput(GetCurrentThreadId(),threadID,   false);
			  }
	}
	else
	{
		wprintf(L"Window Notepad wasn't found\n");
	}

	// if there was SendInput, it also should be seen here
	while(_kbhit())
	{
		wprintf(L"%c",getch());
	}

	// wait for keystroke to exit
	while(!_kbhit());

	return 0;
}