TBS Dropdown Overflow Problem

HTML

<script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.2/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.2/css/bootstrap-combined.min.css">
<div class="container-fluid">
    <div class="row-fluid">
        <div class="span12">
            <ul class="nav nav-tabs">
                <li><a data-toggle="tab"></a>
                </li>
                <li class="active"><a href="#one" data-toggle="tab">Tab One</a>
                </li>
                <li><a href="#two" data-toggle="tab">Tab Two</a>
                </li>
            </ul>
            <div class="tab-content">
                <div id="one" class="tab-pane active">
                    <div class="btn-group">	<a class="btn btn-mini dropdown-toggle" data-toggle="dropdown" href="#">Filter <span class="caret"></span></a>

                        <ul class="dropdown-menu">
                            <li class="nav-header">Admission</li>
                            <li><a href="#">Admitted</a>

                            </li>
                            <li><a href="#">Not Admitted</a>

                            </li>
                            <li class="divider"></li>
                            <li class="nav-header">Payments</li>
                            <li><a href="#">Paid</a>

                            </li>
                            <li><a href="#">Unpaid</a>

                            </li>
                            <li class="divider"></li>
                            <li class="nav-header">Role</li>
                            <li><a href="#">Attendees</a>

                            </li>
                            <li><a href="#">Presenters</a>

                            </li>
                        </ul>
                    </div>
                     <h3>Heading</h3>

                    <p>If only we had some more content, we'd be able to see our dropdown :(</p>
                    <p>I guess I can add a...

CSS

ul.dropdown-menu{
    position: fixed;
    top: 10px;
    left: 20px;
    overflow: visible;
}