Trouble with resource files

[kikelinus]

I have a resource file with a dialog box...When I try to compile the program, it says that there is an undeclaired indentifier for my dialogbox (IDD_ABOUT)....
Here is the code I am using (I have also uploaded the files into a zip file if you wish to download):

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

// function prototype
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
BOOL CALLBACK AboutDlgProc(HWND, UINT, WPARAM, LPARAM);

const char className[] = "myWindowClass";

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
	WNDCLASSEX wc;		// window class
	HWND hwnd;			// handle to a window
	MSG msg;			// message

	// regster the window class
	wc.cbSize = sizeof(WNDCLASSEX);
	wc.style = 0;
	wc.lpfnWndProc = WndProc;
	wc.cbClsExtra = 0;
	wc.cbWndExtra = 0;
	wc.hInstance = hInstance;
	wc.hIcon = LoadIcon(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_MYICON));
	wc.hCursor = LoadCursor(NULL, IDC_ARROW);
	wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
	wc.lpszMenuName = MAKEINTRESOURCE(IDR_MENU1);
	wc.lpszClassName = className;
	wc.hIconSm = (HICON)LoadImage(GetModuleHandle(NULL), MAKEINTRESOURCE(IDI_MYICON), IMAGE_ICON, 16, 16, 0);

	if(!RegisterClassEx(&wc)) {
		MessageBox(NULL, "Failed to initialize class", "Error", MB_ICONEXCLAMATION | MB_OK);
		return 0;
	}

	// creating the window
	hwnd = CreateWindowEx(WS_EX_CLIENTEDGE, className, "Henrique", WS_OVERLAPPEDWINDOW,
		CW_USEDEFAULT, CW_USEDEFAULT, 250, 250, NULL, NULL, hInstance, NULL);

	if(hwnd == NULL) {
		MessageBox(NULL, "Failed to create window", "Error", MB_ICONEXCLAMATION | MB_OK);
		return 0;
	}

	ShowWindow(hwnd, nCmdShow);
	UpdateWindow(hwnd);

	// message loop
	while(GetMessage(&msg, NULL, 0, 0) > 0)	
	{
		TranslateMessage(&msg);
		DispatchMessage(&msg);
	}
	return msg.wParam;
}

// window procedure
LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch(msg) {
	case WM_CLOSE:
		DestroyWindow(hwnd);
		break;

	case WM_DESTROY:
		PostQuitMessage(0);
		break;

	case WM_COMMAND:
    switch(LOWORD(wParam))
    {
		case ID_FILE_EXIT:
			PostMessage(hwnd, WM_CLOSE, 0, 0);
		break;

        case ID_HELP_ABOUT:
        {
            int ret = DialogBox(GetModuleHandle(NULL), 
               MAKEINTRESOURCE(IDD_ABOUT), hwnd, AboutDlgProc);
            if(ret == IDOK){
                MessageBox(hwnd, "Dialog exited with IDOK.", "Notice",
                    MB_OK | MB_ICONINFORMATION);
            }
            else if(ret == IDCANCEL){
                MessageBox(hwnd, "Dialog exited with IDCANCEL.", "Notice",
                    MB_OK | MB_ICONINFORMATION);
            }
            else if(ret == -1){
                MessageBox(hwnd, "Dialog failed!", "Error",
                    MB_OK | MB_ICONINFORMATION);
            }
        }
        break;
    }
break;

	default:
		return DefWindowProc(hwnd, msg, wParam, lParam);
	}
	return 0;
}

// about dialog procedure
BOOL CALLBACK AboutDlgProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
	switch(msg)
	{
	case WM_INITDIALOG:
		return true;

	case WM_COMMAND:
		switch(LOWORD(wParam))
		{
		case IDOK:
			EndDialog(hwnd, IDOK);
			break;

		case IDCANCEL:
			EndDialog(hwnd, IDCANCEL);
			break;
		}
		break;

	default:
		return false;
	}
	return true;
}

Thanks.

[kikelinus]

Problem solved...Thanks anyways