mutliple select form not passing multiple values

I'm running PHP 5.0b3, so I'm not sure whether this is an issue with the version of PHP I'm running. I've got a select field in a form that is allowing multiple selects: <select name="modules" size="10" multiple="multiple" id="modules" style="height: 150px;">

    <option value="2" selected="selected">Banner Manager</option>
    <option value="3" selected="selected">Calendar of Events</option>
    <option value="4">Contacts</option>
    <option value="5">Elections</option>
    <option value="6" selected="selected">Emergency Notices</option>
    <option value="11" selected="selected">Employment Opportunites</option>
    <option value="7" selected="selected">FAQs</option>
    <option value="8" selected="selected">Files & Downloads</option>
    <option value="9">Image Gallery</option>
    <option value="12">Links</option>
    <option value="13" selected="selected">Meetings & Agendas</option>
    <option value="1" selected="selected">News & Articles</option>
    <option value="16" selected="selected">Notices of Public Hearing</option>
    <option value="14" selected="selected">Procurement Opportunities</option>
    <option value="15" selected="selected">Publications</option>
    <option value="18">Weather Information</option>

</select> I'm posting the data to another script, in which I have the following: print_r($_POST); The only thing that is being saved to $_POST['modules'] is the last value (15). When I count($_POST['modules']), I only get 1, so I know that it's not passing back an array of numbers like it should. Am I doing something wrong? -Ben