NHibernate schema validation error in VS2005

NHibernate Error within Visual Studio 2005

Message 1 Could not find schema information for the element 'urn:nhibernate-configuration-2.2:hibernate-configuration'.

How can I resolve this, it seems that Visual Studio 2005 does see the correct xsd file or it doesn't not of it at all.

I have added the following references
NHibernate.dll
log4j.net.dll
Nullables.dll

Here is the my Config.xml file


<?xml version="1.0" encoding="utf-8" ?>
<configuration>
 
    <!-- Add this element -->
    <configSections>
      <section
          name="hibernate-configuration"
          type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate"
        />
    </configSections>



  <hibernate-configuration xmlns='urn:nhibernate-configuration-2.2'      xmlns:xs='http://www.w3.org/2001/XMLSchema'>
    <session-factory>
      <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider</property>
      <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
      <property name="connection.connection_string">removed</property>
      <property name="show_sql">true</property>
      <property name="dialect">NHibernate.Dialect.MsSql2000Dialect</property>
      <property name="use_outer_join">true</property>
      <mapping assembly="testassembly" />
    </session-factory>
  </hibernate-configuration>
</configuration>