Nhibernate在基类上联接了子类和orderby

嗨，我有一个子类，我在包上使用这个子类，但是我想使用基类中的orderby。但是当我通过Nhibernate下订单时，使用子类。有人知道怎么做吗？我把映射放在下面

  <many-to-one name="Type" class="DocumentType" column="DocumentTypeId" not-null="false" cascade="all" />


  <joined-subclass table="PersonDocument"  name="PersonDocument">
    <key column="DocumentId"/>
    <many-to-one name="EventGroupType" class="EventGroupType" column="EventGroupTypeId" not-null="false" cascade="all" />
  </joined-subclass>

</class>

如果我运行sql，那么它会按照PersonDocument.Name进行排序，但它应该是Document.Name

  <many-to-one name="Type" class="DocumentType" column="DocumentTypeId" not-null="false" cascade="all" />


  <joined-subclass table="PersonDocument"  name="PersonDocument">
    <key column="DocumentId"/>
    <many-to-one name="EventGroupType" class="EventGroupType" column="EventGroupTypeId" not-null="false" cascade="all" />
  </joined-subclass>

</class>

谢谢

  <bag name="Documents" cascade="all" order-by="Name" >
    <key column="PersonId"/>
    <one-to-many class="PersonDocument" />
  </bag>


<?xml version="1.0" encoding="utf-8" ?>

  <many-to-one name="Type" class="DocumentType" column="DocumentTypeId" not-null="false" cascade="all" />


  <joined-subclass table="PersonDocument"  name="PersonDocument">
    <key column="DocumentId"/>
    <many-to-one name="EventGroupType" class="EventGroupType" column="EventGroupTypeId" not-null="false" cascade="all" />
  </joined-subclass>

</class>

  <many-to-one name="Type" class="DocumentType" column="DocumentTypeId" not-null="false" cascade="all" />


  <joined-subclass table="PersonDocument"  name="PersonDocument">
    <key column="DocumentId"/>
    <many-to-one name="EventGroupType" class="EventGroupType" column="EventGroupTypeId" not-null="false" cascade="all" />
  </joined-subclass>

</class>

  <many-to-one name="Type" class="DocumentType" column="DocumentTypeId" not-null="false" cascade="all" />


  <joined-subclass table="PersonDocument"  name="PersonDocument">
    <key column="DocumentId"/>
    <many-to-one name="EventGroupType" class="EventGroupType" column="EventGroupTypeId" not-null="false" cascade="all" />
  </joined-subclass>

</class>