Flexible Rails problem

Hello everybody, i'm reading the book Flexible Rails, i'm in page 122
of the pdf, but the login page is not working, the error it gives when
i try to login:

[RPC Fault faultString="HTTP request error"
faultCode="Server.Error.Request" faultDetail="Error: [IOErrorEvent
type="ioError" bubbles=false cancelable=false eventPhase=2 text="Error
#2032: Stream Error. URL: http://localhost:3000/sessions/create_xml"].
URL: /sessions/create_xml"]
  at mx.rpc::AbstractInvoker/http://www.adobe.com/2006/flex/mx/
internal::faultHandler()[E:\dev\3.0.x\frameworks\projects\rpc\src\mx
\rpc\AbstractInvoker.as:216]
  at mx.rpc::Responder/fault()[E:\dev\3.0.x\frameworks\projects\rpc\src
\mx\rpc\Responder.as:49]
  at mx.rpc::AsyncRequest/fault()[E:\dev\3.0.x\frameworks\projects\rpc
\src\mx\rpc\AsyncRequest.as:103]
  at DirectHTTPMessageResponder/errorHandler()[E:\dev\3.0.x\frameworks
\projects\rpc\src\mx\messaging\channels\DirectHTTPChannel.as:343]
  at flash.events::EventDispatcher/dispatchEventFunction()
  at flash.events::EventDispatcher/dispatchEvent()
  at flash.net::URLLoader/redirectEvent()

The methods used are:

From RoR:

sessions_controler.rb

def create_xml
     self.current_user = User.authenticate(params[:login],
params[:password])
        if logged_in?
            if params[:remember_me] == "1"
             self.current_user.remember_me
             cookies[:auth_token] = {
       :value => self.current_user.remember_token,
       :expires => self.current_user.remember_token_expires_at
       }
            end
         render :xml => self.current_user.to_xml
       else
    render :text => "badlogin"
     end
  end

From Flex:

LoginBox.mxml

private function handleAccountLoginResult(event:ResultEvent):void {
        var result:Object = event.result;
        if (result == "badlogin") {
          Alert.show("The username or password is wrong.","Login
Error");
        }
        else {
          dispatchEvent(new LoginEvent(XML(result)));

        }
      }

<mx:HTTPService
    id="svcAccountLogin"
    url="/sessions/create_xml"
    resultFormat="e4x"
    method="POST"
    result="handleAccountLoginResult(event)"/>

LoginEvent.as

package com.pomodo.events
{
  import flash.events.Event;

  public dynamic class LoginEvent extends Event
  {
    public static const LOGIN:String = "login";
    public var user:XML;

    public function LoginEvent(user:XML) {
      super(LOGIN);
      this.user = user;
    }
  }
}

Can anybody please help me?