Comment 2 for bug 278828

I can confirm this issue.

It Looks like the regular user isn't registered with the "dip" group by default.

I tried it this way:

Open terminal.

Add the user to the "dip" group by entering:

sudo adduser USERNAME dip

Log out and in again.

Hope this helps.

(Source: http://www.andreas-janssen.de/debian-tipps-sarge.html.de see: 11. Benutzergruppen )