I am adding a new mimetype for mp4 files to Tridion.  I have followed the instructions on the [Tridion Live Content site here][1].  (login first).

And I have confirmed my settings match the [blog post here.][2]

And then I flushed my browser cache and even restarted the CMS server.  But, I still get the following error:

> The file extension of the selected item is unknown. The specified file
> does not match a supported Multimedia Type.

Any ideas?

  [1]: http://sdllivecontent.sdl.com/LiveContent/content/en-US/SDL_Tridion_2011_SPONE/task_F8456F78DAC540F2A72BC8EC70E2CA4C
  [2]: http://alokbhatt11.blogspot.be/2013/06/upload-mp4-videos-in-to-tridion-cms.html