Logstash on Windows: Error when starting agent

I'm having some trouble when i try to run logstash on windows:

When i run the following command, I get this error message:

Clamp::UsageError: Unrecognised option '-c'
  signal_usage_error at D:/Logging/logstash/vendor/bundle/jruby/1.9/gems/clamp-0
.6.3/lib/clamp/command.rb:103
         find_option at D:/Logging/logstash/vendor/bundle/jruby/1.9/gems/clamp-0
.6.3/lib/clamp/option/parsing.rb:62
       parse_options at D:/Logging/logstash/vendor/bundle/jruby/1.9/gems/clamp-0
.6.3/lib/clamp/option/parsing.rb:18
               parse at D:/Logging/logstash/vendor/bundle/jruby/1.9/gems/clamp-0
.6.3/lib/clamp/command.rb:52
                 run at D:\Logging\logstash\lib\logstash\runner.rb:158
                call at org/jruby/RubyProc.java:271
                 run at D:\Logging\logstash\lib\logstash\runner.rb:175
                main at D:\Logging\logstash\lib\logstash\runner.rb:92
              (root) at D:\Logging\logstash\lib\logstash\runner.rb:215

Command: logstash agent -config D:\Logging\logstash\bin\stdin.conf

My config file looks like:

input { stdin { } } output { stdout {} }

I tried some other configurations (file input, elasticsearch output,..) but the error occurs everytime.

Any idea? Thanks