How do I allow users to edit Custom CiviCRM Fields in their Profile?

This might be a dumb question, but I'm going to ask it anyway. :) I've set up a group of CiviCRM Profile fields compromised of custom data fields, enabled the fields, given access control to the custom CiviCRM data, and installed CiviNode and CiviNode CCK. I've also enabled the custom CiviCRM fields so they show up at the time of user registration in Drupal.

However after a user has registered, if they attempt to go back into their profile and edit the CiviCRM custom data, it's gone. What I see under the "Edit" tab for a user's profile are two secondary tabs, one for "Account settings" and the second for "Personal Information" (the CiviCRM data).

The information on the "Account settings" tab is fine, but when I click on the "Personal Information" there's nothing to be found. Looking at the HTML of the page, there's no fieldset that I would expect to see. Where could it have gone? Is this even a CiviNode issue or possibly something else? Do I have to put code somewhere to get the custom data to display in the Drupal user profile?

As reference, I'm doing all of this as site admin (so I have full access control for everything), and running the following setup: Drupal 5.7, CiviCRM 1.9, MySQL 5.0.45, PHP 5.2.3, Apache 2.2.4 on Windows XP. Thanks.