When trying to setup the "sports" sample, I get the following error:

tkn@tkn-desktop-ubuntu ~/my/ruby/streamlined_samples/sports $ rake app:setup --trace
(in /home/tkn/my/ruby/streamlined_samples/sports)
** Invoke app:setup (first_time)
** Invoke db:mysql:recreate (first_time)
** Invoke db:mysql:drop (first_time)
** Invoke environment (first_time)
** Execute environment
rake aborted!
undefined method `display_format_for' for #<Module:0xb6e4d0fc>
/home/tkn/my/ruby/streamlined_samples/sports/config/environment.rb:64
/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'
/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
(... long stack trace)

Any clues?