Troubleshooting Definition List – Second tab doesn't function

Hi,

1. I’m trying to set a definition list, setting two tabs that will allow leaving comments in two different social media netowrks (Facebook & VK).
The main purpose is that you could leave a comment by pressing the relevant tab.

2. Implementation:

2.1 Test page can be seen here:

http://www.letthemstare.com/test1.php

2.2 Code:

<dl class="tabs">
        <dt class="selected">Facebook</dt>
            <dd class="selected">
                <div class="tab-content">
                    <div class="fb-comments" data-href="http://www.letthemstare.com/catherine-dress-2/" data-num-posts="10" data-width="590"></div>
                </div>
            </dd>
        <dt>Vkontakte</dt>
            <dd>
                <div class="tab-content">
                    <div id="vk_comments"></div>
                    <script type="text/javascript">
                    VK.Widgets.Comments("vk_comments", {limit: 10, width: "590", attach: "*"});
                    </script>
                </div>
            </dd>

    </dl>

Currently, I have two tabs but the second one is not functioning.
Does anyone knows why?
Thanks and regards,

Kfir Silis