Bug#698504: system-config-printer: permission problem though added to lp group

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Package: system-config-printer
Version: 1.2.3-3
Severity: normal

Hello,

I would like that my users can use the brillant system-config-printer
into their x11.

I thus added them to lp group
adduser username lp

So, they should be capable to add their own printer from the network,
eg. 192.168.1.8

but it keeps asking them the root password.

Please a fix.

Thanks
best regards

-- System Information:
Debian Release: 6.0.6
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: i386 (i686)

Kernel: Linux 2.6.32-5-686 (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages system-config-printer depends on:
ii  gnome-icon-theme   2.30.3-2              GNOME Desktop icon theme
ii  python             2.6.6-3+squeeze7      interactive high-level object-orie
ii  python-cups        1.9.48-1              Python bindings for CUPS
ii  python-cupshelpers 1.2.3-3               Python utility modules around the 
ii  python-dbus        0.83.1-1              simple interprocess messaging syst
ii  python-glade2      2.17.0-4              GTK+ bindings: Glade support
ii  python-gnome2      2.28.1-1              Python bindings for the GNOME desk
ii  python-gtk2        2.17.0-4              Python bindings for the GTK+ widge
ii  python-libxml2     2.7.8.dfsg-2+squeeze5 Python bindings for the GNOME XML 
ii  python-notify      0.1.1-2+b2            Python bindings for libnotify
ii  python-support     1.0.10                automated rebuilding support for P

Versions of packages system-config-printer recommends:
ii  cups-pk-helper                0.1.0-3    PolicyKit helper to configure cups
ii  system-config-printer-udev    1.2.3-3    Utilities to detect and configure 

Versions of packages system-config-printer suggests:
pn  python-gnomekeyring           <none>     (no description available)
pn  python-smbc                   <none>     (no description available)
pn  sessioninstaller              <none>     (no description available)

-- no debconf information