While following Lee's tutorial `Limit access to admin modules` (Issue 50), I couldn't find the `Users and Roles` module to add to my limited-access admin page. DNN knows about this module since I've been doing all that stuff as an admin. After much (really, much) searching I finally found how to add this and other `premium` modules. You must be logged in as a supersuser to do the following! Admin - Site Settings - Advanced Settings - Host Settings, you will see an area called Premium Modules. The help for this says: 'Premium modules are only available to specific portals'. So don't try to add the `missing` module again, or copy from the admin tab (though that might work).

Some other info.
I'm using version 05.05.01 (22) Community Edition.
Other premium modules include Lists, Messaging and Scheduler.
My site has two portals (the one I'm working on is a domain alias.

List of core modules
http://www.dnncreative.com/Tutorial...fault.aspx

These forum posts define the problem, but the solutions are inaccurate.
http://www.dotnetnuke.com/Resources...fault.aspx

http://local.dotnetnuke.com/Communi...fault.aspx

I'm having that same problem. Did you ever come up wtih a solution?

Which specific problem? Certain modules not appearing the the Add Module dropdown?

Have you checked the Extensions page to make sure that the module exists? If so, check to see that it is configured so that it can be added to a page.