hola buenas tardes
amigos tengo un problema al iniciar el beef en backtrack5 r3

root@bt:/pentest/web/beef# ./beef
/root/.gem/ruby/1.9.2/gems/bundler-1.5.1/lib/bundler/constants.rb:2:in `<module:Bundler>': uninitialized constant Bundler::RbConfig (NameError)
   from /root/.gem/ruby/1.9.2/gems/bundler-1.5.1/lib/bundler/constants.rb:1:in `<top (required)>'
   from /root/.gem/ruby/1.9.2/gems/bundler-1.5.1/lib/bundler/shared_helpers.rb:4:in `require'
   from /root/.gem/ruby/1.9.2/gems/bundler-1.5.1/lib/bundler/shared_helpers.rb:4:in `<top (required)>'
   from /root/.gem/ruby/1.9.2/gems/bundler-1.5.1/lib/bundler/setup.rb:1:in `require'
   from /root/.gem/ruby/1.9.2/gems/bundler-1.5.1/lib/bundler/setup.rb:1:in `<top (required)>'
   from /pentest/web/beef/core/loader.rb:18:in `require'
   from /pentest/web/beef/core/loader.rb:18:in `<top (required)>'
   from ./beef:42:in `require'
   from ./beef:42:in `<main>'


ya instale el beef
tambien he dado apt-get install blunder
pero nada