What’s wrong with this widget?

Can someone tell me what’s wrong with my widget?

<?php
/*
Plugin Name: My widget
Description: Adds a sidebar widget to let users emplment myplugin without editing the template.
Author: Nate
Version: 0.2
Author URI: http://experiencetheweb.info
*/
function widget_mywid($args) {
    extract($args);
?>
        <?php echo $before_widget; ?>
            <?php echo $before_title
                . 'My Widget'
                . $after_title; ?>
            <?php my_function() ?>

        <?php echo $after_widget; ?>
<?php
}
register_sidebar_widget('My Widget','mywid');
?>