Error: dumper: FATAL must be run setuid root to communicate correctly

This error occurs when an amdump is executed and the setuid root is not set on the dumper file:

These dumps were to tape DailySet1.
The next tape Amanda expects to use is: a new tape.
FAILURE AND STRANGE DUMP SUMMARY:
amanda.transolutions.net  /etc  RESULTS MISSING
dumper: FATAL must be run setuid root to communicate correctly
dumper: FATAL must be run setuid root to communicate correctly
dumper: FATAL must be run setuid root to communicate correctly
dumper: FATAL must be run setuid root to communicate correctly
planner: ERROR Request to amanda.transolutions.net timed out.

Run amcheck on the configuration:

amcheck DailySet1 
Amanda Tape Server Host Check
-----------------------------
WARNING: program /usr/lib/amanda/planner: not setuid-root
WARNING: program /usr/lib/amanda/dumper: not setuid-root
WARNING: program /usr/sbin/amcheck: not setuid-root
Holding disk /etc/amanda/dumps: 60722876 KB disk space available, using 60620476 KB
amcheck-server: slot 1: date 20060519 label DailySet101 (active tape)
amcheck-server: fatal slot 2: Drive not ready after 120 seconds, rewind said "/usr/lib/amanda/chg-zd-mtx:   line 392: mt: command not found" 
ERROR: new tape not found in rack
     (expecting a new tape)
NOTE: skipping tape-writable test
NOTE: info dir /etc/amanda/DailySet1/curinfo/amanda.transolutions.net: does not exist
NOTE: it will be created on the next run.
Server check took 182.582 seconds

Make sure the the gid of the amandabackup user is set to disk:

-bash-3.00$ id amandabackup
uid=33(amandabackup) gid=6(disk) groups=6(disk),501(cvs)

Set the setuid root on the files below:

1. Run as root:
chmod u+s /usr/lib/amanda/planner
chmod u+s /usr/lib/amanda/dumper
chmod u+s /usr/sbin/amcheck