content field user reference populated by view (views2)? Drupal-6.22 

I have numerous content types where one or more users are associated with the type.  On the bottom of the field definition page there is an advanced section where it asks for the name of the view to provide the content.  I've created a view but it is not showing in the drop down in this area. What does one have to do in order to make a view available for this content field drop down?

The field area reads: Advanced - Users that can be referenced (View)

Please provide a URL where this is explained?  

Thanks
The way I understand it, CCK will list all views on your site that return USERS, so, make sure your view is of type USER not NODE.