Gravatar support in WPbook , Comment loop issue

Hello,

I am trying to add gravatar support to the wpbook plugin (http://wordpress.org/extend/plugins/wpbook) I have the functionality mostly done but there is an error with the way the plugin stores the “comment object”. I am able to get the gravatar to show if i use <?php echo get_avatar(get_comment_author_email(), 32 ); ?> inside the comment loop but not if i use <?php echo get_avatar($comment), 32 ); ?>

If someone could explain what the “comment object” is and how wordpress stores this data that would be great. The gravatar will show up on all comments left from WordPress but not the Facebook(R) app created by the plugin.

Thanks,
Brooke