C++ - Sending WM_WM_LBUTTONDOWN to Aion

Hey, can anyone help me? I try to send a Message to Aion via SendMessage():

Code:

#include <iostream>
#include <Windows.h>

using namespace std;

int main()
{
	HWND hWnd = FindWindowA(NULL, "AION Client");
	if(!hWnd)
	{
		cout << "Fail" << endl;
		getchar();
		getchar();
		exit(1);
	}


	Sleep(5000);

	SendMessage(hWnd,WM_LBUTTONDOWN,0,0);
	Sleep(100);
    SendMessage(hWnd,WM_LBUTTONUP,0,0); 
}

But nothing happens. Does anyone know how I can make this work?

THX!