Why aren my Twitter Integration, Twitter feed imports, or Twitter widget working?
If you have protected your tweets at Twitter.com, you would have to unprotect them in order for Tumblr to be able to communicate with your Twitter account. The Twitter API is sometimes overloaded or unavailable. In those cases, tweets will be temporarily unavailable. Finally, Twitter Integration on the Preferences page only works with direct posts to the default blog on your account. It does not work with queued posts or with additional blogs.