Post the /etc/sudoers file and give an example of what your trying to do with the sudo command (syntax).
from knoppix root I:

visudo

then i open the sudoers file with kwrite, edit and save

here's the file:
# sudoers file.
#
# This file MUST be edited with the "visudo" command as root.
#
# See the man page for details on how to write a sudoers file.
#

# Host alias specification

# User alias specification

# Cmnd alias specification

# User privilege specification
root ALL=(ALL) ALL
jMon ALL=(ALL) ALL
# KNOPPIX WARNING: This allows the unprivileged knoppix user to start commands as root
# KNOPPIX WARNING: This is totally insecure and (almost) makes knoppix a second root account.
# KNOPPIX WARNING: Never allow external access to the knoppix user!!!
#knoppix ALL=NOPASSWD: ALL