Trouble with resource files

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):

Code:

---

#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.

Problem solved...Thanks anyways