提高翻译：PO文件无法正常工作(boost translate: po file not work)

我使用的boost ::现场制作多语言exe文件，但它不工作。 exe文件总是输出的 “Hello World”。怎么能输出“您好”？

我使用的示例代码从http://www.boost.org/doc/libs/1_53_0/libs/locale/doc/html/messages_formatting.html

    #include <boost/locale.hpp>
    #include <iostream>

    using namespace std;
    using namespace boost::locale;

    int main()
    {
        generator gen;

        // Specify location of dictionaries
        gen.add_messages_path(".");
        gen.add_messages_domain("hello");

        // Generate locales and imbue them to iostream
        locale::global(gen(""));
        cout.imbue(locale());

        // Display a message using current system locale
        cout << translate("Hello World") << endl;
    }

并作出PO文件和MO文件。 PO文件是：

# SOME DESCRIPTIVE TITLE.
# Copyright (C) YEAR THE PACKAGE'S COPYRIGHT HOLDER
# This file is distributed under the same license as the PACKAGE package.
# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
#
msgid ""
msgstr ""
"Project-Id-Version: messages\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2013-04-26 20:50+0800\n"
"PO-Revision-Date: 2013-04-26 21:44+0800\n"
"Last-Translator: \n"
"Language-Team: LANGUAGE <LL@li.org>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"X-Generator: Poedit 1.5.5\n"
"X-Poedit-SourceCharset: UTF-8\n"

#: main.cpp:21
msgid "Hello World"
msgstr "您好"

林与boost_locale开始过，这是我如何使它工作...