Forum: IronRuby mspec error undefined method `filtered' for MSpecScript:Class

Have any one got this error? and to fix it :-)

c:\ironruby\Merlin\External.LCA_RESTRICTED\Languages\IronRuby\mspec
\default.mspec:12: undefined method `filtered' for MSpecScript:Class
(NoMethodError)
         from C://Documents and Settings/Administrator/.mspecrc:15:in
`load'
         from C://Documents and Settings/Administrator/.mspecrc:15
         from c:/ruby/lib/ruby/gems/1.8/gems/mspec-1.5.11/lib/mspec/
utils/script.rb:72:in `load'
         from c:/ruby/lib/ruby/gems/1.8/gems/mspec-1.5.11/lib/mspec/
utils/script.rb:72:in `load'
         from c:/ruby/lib/ruby/gems/1.8/gems/mspec-1.5.11/lib/mspec/
utils/script.rb:71:in `each'
         from c:/ruby/lib/ruby/gems/1.8/gems/mspec-1.5.11/lib/mspec/
utils/script.rb:71:in `load'
         from c:/ruby/lib/ruby/gems/1.8/gems/mspec-1.5.11/lib/mspec/
utils/script.rb:213:in `main'
         from c:/ruby/lib/ruby/gems/1.8/gems/mspec-1.5.11/bin/mspec:7
         from c:/ruby/bin/mspec:16:in `load'
         from c:/ruby/bin/mspec:16

Thanks in advance.
-Jirapong