NHibernate配置文件的问题

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="hibernate-configuration"
 type="NHibernate.Cfg.ConfigurationSectionHandler, NHibernate"  />
  </configSections>
  <hibernate-configuration  xmlns="urn:nhibernate-configuration-2.2" >
    <session-factory>
      <property name="connection.provider">NHibernate.Connection.DriverConnectionProvider, NHibernate</property>      <property name="connection.driver_class">NHibernate.Driver.SqlClientDriver</property>
      <property name="connection.connection_string">
        server=.;uid=sa;pwd=sa;database=NHibernate
      </property>
      <property name="dialect">NHibernate.Dialect.MsSql2000Dialect </property>
      <property name="show_sql">true</property>
      <property name="proxyfactory.factory_class">NHibernate.ByteCode.LinFu.ProxyFactoryFactory, NHibernate.ByteCode.LinFu</property>
    </session-factory>
  </hibernate-configuration>
</configuration>Configuration config = new Configuration() 实例化的时候出错：NHibernate.Cfg.Configuration”的类型初始值设定项引发异常