When you enable both the content organizer and the awesome SharePoint 2010 Document Sets features, you run into trouble when trying to create a new document set in a document library.
The descriptive error you will get is:
Unable to create a Document Set in this location because of the Content Organizer settings. Please contact your administrator.
SharePoint tries to route the document set which it shouldn't even try. You can disable this functionality by going to Site Settings -> Content Organizer Settings -> Clear the check-box for 'Require users to use the organizer when submitting new content to libraries with one or more organizer rules pointing to them'.
Now you will be able to create document sets again !
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Kowalski: Skipper, look.
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[Catches the manual and smashes the bulb with it]
Skipper: Problemo solved.