Redmine

use Nitnami redmine 2.3.2 ,I want to install the redmine_timesheet_extensions plugins.I follow the redmine install step in "http://www.redmine.org/wiki/redmine/Plugins" .
I download the plugins in c:\bitnami\redmine-2.3.0-2\apps\redmine\htdocs\plugins
and use the command "git clone git://github.com/nicStuff/redmine_timesheet_extensions.git"
but when I put in the command "rake redmine:plugins:migrate RAILS_ENV=production"
it say "*rake aborted!
No Rakefile found (looking for: rakefile, Rakefile, rakefile.rb, Rakefile.rb)

(See full trace by running task with --trace)

C:\BitNami\redmine-2.3.2-0\apps\redmine>cd htdocs\plugins\redmine_timesheet_exte
nsions

C:\BitNami\redmine-2.3.2-0\apps\redmine\htdocs\plugins\redmine_timesheet_extensi
ons>rake redmine:plugins:migrate RAILS_ENV=production
(in C:/BitNami/redmine-2.3.2-0/apps/redmine/htdocs)
rake aborted!
C:/BitNami/redmine-2.3.2-0/apps/redmine/htdocs/plugins/redmine_timesheet_extensi
ons/init.rb:29: invalid multibyte char (US-ASCII)
C:/BitNami/redmine-2.3.2-0/apps/redmine/htdocs/plugins/redmine_timesheet_extensi
ons/init.rb:29: invalid multibyte char (US-ASCII)
C:/BitNami/redmine-2.3.2-0/apps/redmine/htdocs/plugins/redmine_timesheet_extensi
ons/init.rb:29: syntax error, unexpected $end, expecting keyword_end
...el tempo impiegato su attivit�� e progetti.'
... ^

Tasks: TOP => redmine:plugins:migrate => environment
(See full trace by running task with --trace)"*
Then i restart the redmine it can't work!
help me how to do this?
thank you