DialogBox() returning -1 and GetLastError()=0 ?

[deathpum]

Hello, I have a dialog box designed in Visual C++ 2010 SP1 resource editor and its id is IDD_DIALOG4. When I try to create it using DialogBox() API, the function returns -1 and GetLastError() returns 0. Note: WM_INITDIALOG is not being called.
Can anybody help me?

// main.cpp

void showDlg(HINSTANCE hInstance, HWND hwndParent)
{
	int dlgRet = DialogBoxA( hInstance, MAKEINTRESOURCE(IDD_DIALOG4), hwndParent, (DLGPROC)MyDlgProc );
	if(dlgRet==-1)
	{
		msgbox("error on creating dlg: %08X", GetLastError());
		return;

	}
}

// Dialog procedure
LRESULT CALLBACK MyDlgProc( HWND hWndDlg, UINT Msg, WPARAM wParam, LPARAM lParam )
{
	switch( Msg )
	{
		case WM_INITDIALOG:
			msgbox("WM_INITDIALOG");
			return TRUE;
		break;
		case WM_COMMAND:
			switch( wParam )
			{
				case IDC_BUTTON_COPY:
					msgbox("IDC_BUTTON_COPY");
					return TRUE;
				break;
				case IDCANCEL: // close
					EndDialog( hWndDlg, 0 );
					return TRUE;
				break;
			}
			return TRUE;
		break;
		case WM_CLOSE:
			EndDialog( hWndDlg, 0 );
			return TRUE;
		break;
		default:
			return FALSE;
	}
}

// main.rc

IDD_DIALOG4 DIALOGEX 0, 0, 317, 151
STYLE DS_SETFONT | DS_MODALFRAME | DS_FIXEDSYS | WS_POPUP | WS_CAPTION | WS_SYSMENU
CAPTION "Result"
FONT 8, "MS Shell Dlg", 400, 0, 0x1
BEGIN
    PUSHBUTTON      "Close",IDCANCEL,260,130,50,14
    LTEXT           "Text1:",IDC_STATIC1,15,16,69,8
    LTEXT           "Text2",IDC_STATIC_SIGN_TEXTSTYLE,92,17,62,8
    PUSHBUTTON      "Copy to clipboard",IDC_BUTTON_COPY,7,54,69,9
    CONTROL         "<a>SysLink2</a>",IDC_SYSLINK2,"SysLink",WS_TABSTOP,90,37,60,14
    CONTROL         "",IDC_RICHEDIT_CODESTYLEWITHFP,"RichEdit20A",ES_MULTILINE | ES_AUTOVSCROLL | ES_AUTOHSCROLL | ES_NOHIDESEL | WS_BORDER | WS_TABSTOP,7,65,303,59
END