Custom User Fields in MODx Evolution 1.0- OnWUsrFormRender

I'm trying to add custom user fields开发者_C百科 to the Web Users Manager area in MODx Evolution 1.0 via a custom plugin. I'm in the early stages and can't get the 'OnWUsrFormRender' hook to do anything. Any ideas?

Here's my test plugin code:

<?php
$e = &$modx->Event;
switch($e->name){
    case "OnWUsrFormRender":
        $fields = '
            Test Info: <input type="text" name="test"/>
        ';
        $e->output($fields);    //this doesn't show up
        echo 'testing';    //this doesn't show up
        break;
}
?>

(PS- I've tried WebUserPE and PPP, but neither of them are good for my situation...)

You must not include

 <?php ?>

tags in plugins besides that the code works fine.