Error while starting Logstash 2.1.3

hi,

I am a newbie trying to load up the ELK stack. I am trying to start logstash version 2.1.3, but I see the following error -

bin/logstash -e 'input { stdin { } } output { stdout {} }'
NameError: undefined method 'new' for class '#Class:0x2f8e8219'
private_class_method at org/jruby/RubyModule.java:2328
Rational at /auto/tools/lib/ruby/1.8/rational.rb:97
(root) at /auto/tools/lib/ruby/1.8/rational.rb:64
require at org/jruby/RubyKernel.java:1040
(root) at /auto/tools/lib/ruby/1.8/date.rb:1
require at org/jruby/RubyKernel.java:1040
(root) at /auto/tools/lib/ruby/1.8/date.rb:196
require at org/jruby/RubyKernel.java:1040
(root) at /auto/tools/lib/ruby/site_ruby/1.8/rubygems/specification.rb:1
require at org/jruby/RubyKernel.java:1040
(root) at /auto/tools/lib/ruby/site_ruby/1.8/rubygems/specification.rb:1
load at org/jruby/RubyKernel.java:1059
(root) at /auto/tools/lib/ruby/site_ruby/1.8/rubygems.rb:1

This error is not seen when I start version 1.4.3. Can someone please help me figure out what is wrong? I couldn't find an exact match for this error in the discussion forum, but apologies if this has been asked before.

Thanks!