Homebrew Installation "staff group" Error

I'm trying to use the Homebrew install script:

/usr/bin/ruby -e "$(curl -fsSL https://raw.github.com/gist/323731)"

It doesn't work:

This script requires the user <my_username> to be in the staff group. If this
sucks for you then you can install Homebrew in your home directory or however
you please; please refer to the website. If you still want to use this script
the following command should work:

    dscl /Local/D开发者_运维技巧efault -append /Groups/staff GroupMembership $USER

Neither does that last line, which returns this when run with either $USER or my actual username:

<main> attribute status: eDSPermissionError
<dscl_cmd> DS Error: -14120 (eDSPermissionError)

How am I supposed to install this? Everywhere I read about people using this install script on the web, it apparently works like gangbusters.

I was experiencing the same problem on Lion 10.7.1 I followed the command listed here: http://obfuscurity.com/2011/07/Fixing-Group-Permissions-after-Migrating-to-OS-X-Lion

sudo dscl . append /Groups/staff GroupMembership `whoami`

And I am now able to proceed with the homebrew installation.