public IList<DataTransfer.Order> GetOrdersByCustomerID(int CustomerID)
{
   return _session.CreateQuery("select from Order o").List<Order>();
}

Error   1   TestCase 'orderTest.canGetOrderByCustomerID'
failed: could not execute query
[ select order0_.id as id0_, order0_.version as version0_, order0_.orderdate as orderdate0_, order0_.customer as customer0_ from Orders order0_ ]
[SQL: select order0_.id as id0_, order0_.version as version0_, order0_.orderdate as orderdate0_, order0_.customer as customer0_ from Orders order0_]
NHibernate.ADOException
Message: could not execute query
[ select order0_.id as id0_, order0_.version as version0_, order0_.orderdate as orderdate0_, order0_.customer as customer0_ from Orders order0_ ]
[SQL: select order0_.id as id0_, order0_.version as version0_, order0_.orderdate as orderdate0_, order0_.customer as customer0_ from Orders order0_]
Source: NHibernate
StackTrace:
   at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters)
   at NHibernate.Loader.Loader.List(ISessionImplementor session, QueryParameters queryParameters, ISet`1 querySpaces, IType[] resultTypes)
   at NHibernate.Hql.Classic.QueryTranslator.List(ISessionImplementor session, QueryParameters queryParameters)
   at NHibernate.Engine.Query.HQLQueryPlan.PerformList(QueryParameters queryParameters, ISessionImplementor session, IList results)
   at NHibernate.Impl.SessionImpl.List(String query, QueryParameters queryParameters, IList results)
   at NHibernate.Impl.SessionImpl.List[T](String query, QueryParameters parameters)
   at NHibernate.Impl.QueryImpl.List[T]()
   at mvcstore.data.OrderRepository.GetOrdersByCustomerID(Int32 CustomerID) in C:\Documents and Settings\Administrator\My Documents\Visual Studio 2008\Projects\mvcstore\mvcstore.data\OrderRepository.cs:line 21
   at mvcstore.test.orderTest.canGetOrderByCustomerID() in C:\Documents and Settings\Administrator\My Documents\Visual Studio 2008\Projects\mvcstore\mvcstore.test\orderTest.cs:line 27
Inner Exception
System.IO.FileNotFoundException
Message: Could not load file or assembly 'Castle.Core, Version=1.0.3.0, Culture=neutral, PublicKeyToken=407dd0808d44fbdc' or one of its dependencies. The system cannot find the file specified.
Source: NHibernate
StackTrace:
   at NHibernate.Proxy.Poco.Castle.CastleProxyFactory.GetProxy(Object id, ISessionImplementor session)
   at NHibernate.Tuple.Entity.AbstractEntityTuplizer.CreateProxy(Object id, ISessionImplementor session)
   at NHibernate.Persister.Entity.AbstractEntityPersister.CreateProxy(Object id, ISessionImplementor session)
   at NHibernate.Event.Default.DefaultLoadEventListener.CreateProxyIfNecessary(LoadEvent event, IEntityPersister persister, EntityKey keyToLoad, LoadType options, IPersistenceContext persistenceContext)
   at NHibernate.Event.Default.DefaultLoadEventListener.ProxyOrLoad(LoadEvent event, IEntityPersister persister, EntityKey keyToLoad, LoadType options)
   at NHibernate.Event.Default.DefaultLoadEventListener.OnLoad(LoadEvent event, LoadType loadType)
   at NHibernate.Impl.SessionImpl.FireLoad(LoadEvent event, LoadType loadType)
   at NHibernate.Impl.SessionImpl.InternalLoad(String entityName, Object id, Boolean eager, Boolean isNullable)
   at NHibernate.Type.EntityType.ResolveIdentifier(Object id, ISessionImplementor session)
   at NHibernate.Type.EntityType.ResolveIdentifier(Object value, ISessionImplementor session, Object owner)
   at NHibernate.Engine.TwoPhaseLoad.InitializeEntity(Object entity, Boolean readOnly, ISessionImplementor session, PreLoadEvent preLoadEvent, PostLoadEvent postLoadEvent)
   at NHibernate.Loader.Loader.InitializeEntitiesAndCollections(IList hydratedObjects, Object resultSetId, ISessionImplementor session, Boolean readOnly)
   at NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
   at NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies)
   at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters)   C:\Documents and Settings\Administrator\My Documents\Visual Studio 2008\Projects\mvcstore\mvcstore.data\OrderRepository.cs   21   

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="DataTransfer" namespace="DataTransfer">
  <class name="DataTransfer.Order,DataTransfer" table="Orders">
    <id name="id" column="id" type="Int32" unsaved-value="0">
      <generator class="native"/>
    </id>
    <version name="version" column="version" type="Int32" unsaved-value="0"/>
    <property name="orderdate" column="orderdate" type="DateTime" not-null="true"/>
    <many-to-one name="customer" column="customer" class="DataTransfer.Customer,DataTransfer" not-null="true"/>
  </class>
</hibernate-mapping>

public class Order
    {
        public virtual int id { get; set; }
        public virtual int version { get; set; }
        public virtual DateTime orderdate { get; set; }
        public virtual Customer customer { get; set; }
    }