[CentOS] screen detatch

The man page for screen says that I can create a detatched screen 
running with a set command in it by doing this:

$ screen -dm $command

However, it doesn't work.  Screen exits without creating the detached
screen.  

If I say 

$ screen $command

...I get dropped into a screen session running $command as I would 
expect.

What's the magic invocation I'm missing?

Also, the next step will be for root to launch said screen session as
someone else during boot time; am I asking for trouble by trying it?

# su - user -c screen -dmS $Label $command

Thanks for any insights or pointers to web resources I can use to
learn from.  
-- 
 /\oo/\
/ /()\ \ David Mackintosh | 
         dave at xdroop.com  | http://www.xdroop.com
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