WMP Plugin not showing up in the plugin panel?

I just downloaded the WMD Editor plugin.
For some reason is not showing up in the Plugins menu.

the folder is called wmd-editor/

wmd-editor.php:

<?php
/*
Plugin Name: WMD Editor
Plugin URI: http://c.hadcoleman.com/wordpress/wmd-editor
Description: Adds the <a href="http://wmd-editor.com/">WMD Editor</a> to the comment field, to make life easier for your commenters.
Version: 1.0
Author: Chad Coleman
Author URI: http://c.hadcoleman.com
 */

/*
This is a simple plugin that just adds the javascript call to the header of your template. You can gather more info on this project at http://code.google.com/p/wmd/
*/ 

    // function for head output sytles
    function wmd_header() {
        global $cb_path;
        $cb_path = get_bloginfo('wpurl')."/wp-content/plugins/wmd-editor";  //URL to the plugin directory
        $hHead = "\n"."<!-- Start WMD Editor -->"."\n";
        $hHead .= " <script language=\"javascript\" type=\"text/javascript\" src=\"{$cb_path}/wmd.js\" ></script>\n";
        $hHead .= "<!-- End WMD Editor -->"."\n";
        print($hHead);
    }

    add_action('wp_head', 'wmd_header'); ?>

Must be something you have installed or custom code causing the issue, it appears just fine for me.

If your question was actually why there’s no additional menu item on the admin side then the answer would be because not every plugin has an admin page, some provide configuration options, others just do something with no configurable options(depends on the intent of the author i suppose).

Hope i could help in any case..