useradd fails

[Marc Balmer <marc_(_at_)_msys_(_dot_)_ch>]

Sorry if this is a FAQ (at least I did not find it in the FAQ...):

I am trying to add the sshd privsep user with the command

# useradd -u 27 -g 27 -d /var/empty -s /sbin/nologin sshd

I get:

useradd: can't obtain pw_lock: File exists

Thanks 4 help...
Marc