I can't work this out

This is my code:

Code:

#include <tchar.h>
#include "resource.h"

BOOL MainDialogProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
	switch (uMsg)
	{
	case WM_COMMAND:
		return MainDialog_OnCommand(hWnd, LOWORD(wParam), HIWORD(wParam), (HWND)lParam);

	case WM_CLOSE:
		EndDialog(hWnd, 0);
		return TRUE;
	}
	return FALSE;
}

BOOL MainDialog_OnCommand(HWND hWnd, WORD wCommand, WORD wNotify, HWND hControl)
{
	switch (wCommand)
	{
	case IDOK:
		MessageBox(hWnd, _T("Bye-bye world!"), _T("Sample Application"), MB_OK);

		// fall through

	case IDCANCEL:
		EndDialog(hWnd, wCommand);
		break;
	}
	return TRUE;
}



int _tmain(void)
{
	DialogBoxParam(GetModuleHandle(NULL), MAKEINTRESOURCE(IDD_DIALOG1),
		NULL, (DLGPROC)MainDialogProc, 0);
	return 0;
}

When I go to complie it it comes back with two warnings:

dialog.c: 10 missing prototype for MainDialog_OnCommand

and

dialog.c: 20 declaration of 'MainDialog_OnCommand' does not match previous declaration at dialog.c: 10

Please help me thanks
Daniel Granger

put this line above MainDialogProc:

BOOL MainDialog_OnCommand(HWND hWnd, WORD wCommand, WORD wNotify, HWND hControl);