Mine

/home/cso%cat wx.rb 
require "wx"
include Wx

class HelloWorld < App
   def on_init
     helloframe = Frame.new(nil, -1, "Hello World")
     StaticText.new(helloframe,-1,"Hello World")
     helloframe.show()
   end
end

HelloWorld.new.main_loop

/home/cso%ruby wx.rb
./wx.rb:2: uninitialized constant Wx (NameError)
        from wx.rb:1:in `require'
        from wx.rb:1
/home/cso%