Why does Kickstart Installation of Red Hat Enterprise Linux 6.1 fail with message "ValueError: min() arg is an empty sequence" ?

Issue

• Why does Kickstart Installation of Red Hat Enterprise Linux 6.1 fail with message "ValueError: min() arg is an empty sequence" ?
• Following traceback was logged into the /tmp/anaconda.logfile

07:45:45,022 INFO    : All kickstart %%traceback script(s) have been run
07:45:45,024 CRITICAL: anaconda 13.21.117 exception report
Traceback (most recent call first):
  File "/usr/lib/anaconda/kickstart.py", line 573, in execute
    device = min(devices.keys())
  File "/usr/lib/anaconda/kickstart.py", line 1182, in execute
    obj.execute(self.anaconda)
  File "/usr/bin/anaconda", line 1103, in <module>
    ksdata.execute()
ValueError: min() arg is an empty sequence