Redmine

Hi, I met some difficulties on installing plugin onto Bitnami Redmine.
To install Bitnami Redmine itself, it is very easy.

But to install plugin, it is so frustrating!

My OS: Windows8 64 bits

（1）
First, I found this instruction below:
http://wiki.bitnami.com/Applications/BitNami_Redmine_Stack#How_to_install_a_plugin_on_Redmine.3f

According to it, I need to install the plugin（KanBan：https://github.com/edavis10/redmine_kanban）here C:\Bitnami\redmine-2.5.1-2\apps\redmine\htdocs\plugins，so now there is a new directory 'redmine_kanban' under it.

（2）
Also I can find an installation instruction on the plugin's Github page: https://github.com/edavis10/redmine_kanban
It tells me that I need to do this：gem install aasm block_helpers
I did it on my cmd of my Win8

（3）
The Github instrcution says that the plugin should be put here：vendor/plugins/redmine_kanban
It is different from the Bitnami's instruction. And the path it mentions does not exist at all
OK, so I create the path and copy the plugin there.
So now I have two copies, just to ensure it can work.

（4）
Then, According to the Github instruction, I need to do this: rake db:migrate_plugins
Before that, I double click 'use_redmine.bat' and then it pops up a new cmd with the right environment setting，and then I execute the above command. Noe I get the errors:
C:\Bitnami\redmine-2.5.1-2\apps\redmine\htdocs\plugins>rake db:migrate_plugins
(in C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs)
rake aborted!
You have already activated rake 0.9.2.2, but your Gemfile requires rake 10.1.1. Prepending `bundle exec` to your command may solve this.

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

（5）
I searched from the internet and a lot of feedback says that just following the hint above, so I did this and got new errors：
C:\Bitnami\redmine-2.5.1-2\apps\redmine\htdocs\plugins>bundle exec rake db:migrate_plugins
(in C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs)
rake aborted!
cannot load such file -- aasm
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `block in require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/plugins/redmine_kanban/init.rb:3:in `<top (required)>'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `block in require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/lib/redmine/plugin.rb:133:in `block in load'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/lib/redmine/plugin.rb:124:in `each'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/lib/redmine/plugin.rb:124:in `load'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/config/initializers/30-redmine.rb:19:in `<top (required)>'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:245:in `load'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:245:in `block in load'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:245:in `load'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/engine.rb:593:in `block (2 levels) in <class:Engine>'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/engine.rb:592:in `each'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/engine.rb:592:in `block in <class:Engine>'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/initializable.rb:30:in `instance_exec'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/initializable.rb:30:in `run'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/initializable.rb:55:in `block in run_initializers'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/initializable.rb:54:in `each'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/initializable.rb:54:in `run_initializers'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/application.rb:136:in `initialize!'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/railtie/configurable.rb:30:in `method_missing'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/config/environment.rb:14:in `<top (required)>'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `block in require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:236:in `load_dependency'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.17/lib/active_support/dependencies.rb:251:in `require'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/application.rb:103:in `require_environment!'
C:/Bitnami/redmine-2.5.1-2/apps/redmine/htdocs/vendor/bundle/ruby/1.9.1/gems/railties-3.2.17/lib/rails/application.rb:305:in `block (2 levels) in initialize_tas
ks'
Tasks: TOP => db:migrate_plugins => redmine:plugins:migrate => environment
(See full trace by running task with --trace)

As you can see, aasm is installed at the beginning. But now it told me that aasm is not installed...
So what does this mean? And how to proceed?
Thank you for any help!