Can't execute demo

[zaknixon]

Tried installation instructions, but this is the output I get:

Zak-Nixons-iMac:Projects znixon$ git clone git://github.com/timcharper/calendar_date_select_demo.git
Initialized empty Git repository in /Users/znixon/Projects/calendar_date_select_demo/.git/
remote: Counting objects: 152, done.
remote: Compressing objects: 100% (78/78), done.
remote: Total 152 (delta 53), reused 152 (delta 53)
Receiving objects: 100% (152/152), 67.34 KiB, done.
Resolving deltas: 100% (53/53), done.
Zak-Nixons-iMac:Projects znixon$ cd calendar_date_select_demo
Zak-Nixons-iMac:calendar_date_select_demo znixon$ git submodule init && git submodule update
Submodule 'vendor/plugins/calendar_date_select' (git://github.com/timcharper/calendar_date_select.git) registered for path 'vendor/plugins/calendar_date_select'
Initialized empty Git repository in /Users/znixon/Projects/calendar_date_select_demo/vendor/plugins/calendar_date_select/.git/
remote: Counting objects: 1516, done.
remote: Compressing objects: 100% (551/551), done.
remote: Total 1516 (delta 924), reused 1351 (delta 830)
Receiving objects: 100% (1516/1516), 226.02 KiB | 129 KiB/s, done.
Resolving deltas: 100% (924/924), done.
Submodule path 'vendor/plugins/calendar_date_select': checked out '68bdbf598b2f0271df1301869fc6940333802d66'
Zak-Nixons-iMac:calendar_date_select_demo znixon$ script/server
/Users/znixon/Projects/calendar_date_select_demo/config/boot.rb:86:in load_rubygems': undefined method>=' for nil:NilClass (NoMethodError)
from /Users/znixon/Projects/calendar_date_select_demo/config/boot.rb:52:in load_initializer' from /Users/znixon/Projects/calendar_date_select_demo/config/boot.rb:39:inrun'
from /Users/znixon/Projects/calendar_date_select_demo/config/boot.rb:11:in boot!' from /Users/znixon/Projects/calendar_date_select_demo/config/boot.rb:109:in<top (required)>'
from script/server:2:in require' from script/server:2:in

'

I am running Ruby 1.9 and Rails 2.3.5.