Bitmap change on button press..

[Code_Nerd]

I wrote this as a lead up to something I need to develop further down the track..
All I want to do at the moment is change the bitmap image when the button is pressed!

It is not working this way, and I am stuck for ideas ATM!
Can anyone tell me why it is not working correctly..

Cheers

#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <commctrl.h>
#include <iostream>
#include "Resource.h"

using namespace std;

#pragma comment(lib, "comctl32.lib")


INT_PTR CALLBACK DlgProc( HWND hwnd , UINT msg , WPARAM wparam , LPARAM lparam)
{
	HWND Pic  = GetDlgItem(hwnd, IDC_GREEN);
	HWND Button = GetDlgItem(hwnd, IDC_BUTTON1);
	
	switch(msg)
	{
	case WM_INITDIALOG:
		{
			static HBITMAP hbmp;
	
			hbmp = (HBITMAP)LoadImage(0, MAKEINTRESOURCE(IDB_GREEN), IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE);
			SendMessage(Pic, BM_SETIMAGE, IDC_GREEN, (LPARAM)hbmp);
			SendMessage(hwnd, WM_SETICON, ICON_SMALL, (LPARAM)LoadIcon(GetModuleHandle(0), MAKEINTRESOURCE(0)));
		}
	break;

	case WM_COMMAND:
		switch(HIWORD(wparam))
		{
			case BN_CLICKED:
					if(LOWORD(wparam) == IDC_BUTTON1)
					{
						//MessageBox(hwnd, "check for Message", 0 ,0);
						static HBITMAP hbmp = (HBITMAP)LoadImage(0, MAKEINTRESOURCE(IDB_RED), IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE | LR_LOADTRANSPARENT);	
						SendMessage(Pic, BM_SETIMAGE, IDC_GREEN, (LPARAM)hbmp);
					}
			break;
		}
	break;
		
	case WM_CLOSE:
		{
			PostQuitMessage(0);
		}
	break;		
			
	}
	return false;
}

INT WINAPI WinMain(HINSTANCE hinstance, HINSTANCE hprevinstance,
    LPSTR lpcmdline, int ncmdshow)
{
	
	InitCommonControls();
	
	DialogBox(hinstance, MAKEINTRESOURCE(IDD_MAIN), 0, DlgProc);
        
    return 0;
}