Redmine

Hi i am getting error restarting redmine when i put the slac_redmine plugins under redmine\plugins folder.

Appreciate your help on this..

Environment:
Redmine version 2.4.3.stable
Ruby version 1.8.7-p352 (2011-06-30) [i386-linux]
Rails version 3.2.16
Environment production
Database adapter Mysql2
SCM:
Git 1.7.1
Filesystem
Redmine plugins:
no plugin installed

/var/www/redmine
[root@splunk redmine]# ll plugins/
total 12
rw-rw-r- 1 1000 1000 31 Feb 8 16:19 README
drwxr-xr-x 5 root root 4096 Feb 25 09:16 redmine_slack
drwxr-xr-x 2 root root 4096 Feb 23 20:09 temp
[root@splunk redmine]# ruby script/rails server webrick e production
=> Booting WEBrick
=> Rails 3.2.16 application starting in production on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:317:in `depend_on': No such file to load - httpclient (LoadError)
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:225:in `require_dependency'
from /var/www/redmine-2.4.3/plugins/redmine_slack/init.rb:3
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:251:in `require'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:251:in `require'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:236:in `load_dependency'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:251:in `require'
from /var/www/redmine-2.4.3/lib/redmine/plugin.rb:133:in `load'
from /var/www/redmine-2.4.3/lib/redmine/plugin.rb:124:in `each'
from /var/www/redmine-2.4.3/lib/redmine/plugin.rb:124:in `load'
from /var/www/redmine-2.4.3/config/initializers/30-redmine.rb:19
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:245:in `load'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:245:in `load'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:236:in `load_dependency'
from /usr/lib/ruby/gems/1.8/gems/activesupport-3.2.16/lib/active_support/dependencies.rb:245:in `load'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/engine.rb:593
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/engine.rb:592:in `each'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/engine.rb:592
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/initializable.rb:30:in `instance_exec'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/initializable.rb:30:in `run'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/initializable.rb:55:in `run_initializers'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/initializable.rb:54:in `each'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/initializable.rb:54:in `run_initializers'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/application.rb:136:in `initialize!'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/railtie/configurable.rb:30:in `send'
from /usr/lib/ruby/gems/1.8/gems/railties-3.2.16/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /var/www/redmine-2.4.3/config/environment.rb:14
from /var/www/redmine-2.4.3/config.ru:3:in `require'
from /var/www/redmine-2.4.3/config.ru:3
from /usr/lib/ruby/gems/1.8/gems/rack-1.4.5/lib/rack/builder.rb:51:in `instance_eval'
from /usr/lib/ruby/gems/1.8/gems/rack-1.4.5/lib/rack/builder.rb:51:in `initialize'
from /var/www/redmine-2.4.3/config.ru:0:in `new'
from /var/www/redmine-2.4.3/config.ru:0