RadRails error when creating new project

i just installed RadRails. Now i want to create a new project. It creates the directory structure and the gives this error. Can somebody tell me what's the problem?

<internal:lib/rubygems/custom_require>:29:in `require': 126: Das angegebene Modul wurde nicht gefunden.   - c:/ruby/lib/ruby/gems/1.9.1/gems/mongrel-1.1.5-x86-mswin32-60/lib/http11.so (LoadError)
 from <internal:lib/rubygems/custom_require>:29:in `require'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `block in require'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:521:in `new_constants_in'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `require'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/mongrel-1.1.5-x86-mswin32-60/lib/mongrel.rb:12:in `<top (required)>'
 from <internal:lib/rubygems/custom_require>:33:in `require'
 from <internal:lib/rubygems/custom_require>:33:in `rescue in require'
 from <internal:lib/rubygems/custom_require>:29:in `require'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `block in require'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:521:in `new_constants_in'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `require'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler/mongrel.rb:1:in `<top (required)>'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `const_get'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `block in get'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `each'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `get'
 from c:/ruby/lib/ruby/gems/1.9.1/gems/rails-2.3.4/lib/commands/server.rb:45:in `<top (required)>'
 from <internal:lib/rubygems/custom_require>:29:in `require'
 from <internal:lib/rub开发者_如何学Cygems/custom_require>:29:in `require'
 from script/server:3:in `<top (required)>'
 from -e:2:in `load'
 from -e:2:in `<main>'

Ruby 1.9 is not compatible with RadRails2

https://radrails.tenderapp.com/discussions/problems/314-while-starting-server-i-get-126-the-specified-module-could-not-be-found