Unknown entity class: NHibernateFirstApp.Use

Why am i getting this exception?

This is my Class code: User.cs
using System;

namespace NHibernateFirstApp
{
public class User
{
private string id;
private string userName;
private string password;
private string emailAddress;
private DateTime lastLogon;


public User()
{
}

public string Id
{
get { return id; }
set { id = value; }
}

public string UserName
{
get { return userName; }
set { userName = value; }
}

public string Password
{
get { return password; }
set { password = value; }
}

public string EmailAddress
{
get { return emailAddress; }
set { emailAddress = value; }
}

public DateTime LastLogon
{
get { return lastLogon; }
set { lastLogon = value; }
}
}
}

Config File:
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<configSections>
<section
name="nhibernate"
type="System.Configuration.NameValueSectionHandler, System, Version=1.0.5000.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"
/>
</configSections>

<nhibernate>
<add
key="hibernate.connection.provider"
value="NHibernate.Connection.DriverConnectionProvider"
/>
<add
key="hibernate.dialect"
value="NHibernate.Dialect.SQLServerDialect"
/>
<add
key="hibernate.connection.driver_class"
value="NHibernate.Driver.SqlClientDriver"
/>
<add
key="hibernate.connection.connection_string"
value="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\User.mdf;Integrated Security=True;User Instance=True"
/>
</nhibernate>
</configuration>

My Hbm file:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0">
<class name="NHibernateFirstApp.User, NHibernateFirstApp" table="users">
<id name="Id" column="LogonId" type="String" length="20">
<generator class="assigned" />
</id>
<property name="UserName" column="Name" type="String" length="40"/>
<property name="Password" type="String" length="20"/>
<property name="EmailAddress" type="String" length="40"/>
<property name="LastLogon" type="DateTime"/>
</class>
</hibernate-mapping>

MY App code:
Configuration cfg = new Configuration();
cfg.AddAssembly("NHibernateFirstApp");


ISessionFactory factory = cfg.BuildSessionFactory();
ISession session = factory.OpenSession();
ITransaction transaction = session.BeginTransaction();

User newUser = new User();
newUser.Id = "joe_cool";
newUser.UserName = "Joseph Cool";
newUser.Password = "abc123";
newUser.EmailAddress = "joe@cool.com";
newUser.LastLogon = DateTime.Now;

// Tell NHibernate that this object should be saved
session.Save(newUser);

// commit all of the changes to the DB and close the ISession
transaction.Commit();
session.Close();

Check the property "Build Action" of your xml file. It should be set to "Embedded Resource".

Antonella :)