Avatar Plugin

I have installed the Avatar plugin into my WPMU site. However, it shows this notice:

Warning: Missing argument 3 for ridwpa_custom_column_user_id_25() in /home/ambition/public_html/wp-content/plugins/reveal-ids-for-wp-admin-25/reveal-ids-for-wp-admin-25.php on line 299

Following is the picture of this notification.

Please let me know what is this and how can I solve it. It this a common problem or it is something I have to get rid of it as soon as possible. Please advise. Thanks.