[sudo-users] sudo for user lp

[Johannes Köster]

Hello there,
I want to use sudo in a cups backend. As cups runs as user lp, I need
the following for the user:

in sudoers:
lp      ALL=(johannes) NOPASSWD: thecommand


and I use the following command in the cups backend: sudo -u johannes
thecommand

The problem is, that sudo asks for a password although I thought that I
have enabled passwordless execution for the command.

So what else do I have to do for user lp?

Thank you very much for your help.
My system is Debian Lenny.

Johannes Köster