<hibernate-mapping>
    <class name="Contact" table="CONTACTS">
      <id name="id" type="long" unsaved-value="null">
           <generator class="identity"/>
        </id>
        <property name="email"/>
        <property name="fax"/>
        <property name="firstName"/>
        <property name="gender"/>
        <property name="lastName"/>
        <property name="middleName"/>
        <property name="mobileNumber"/>
        <property name="note"/>
        <property name="phone"/>
        <property name="phoneExtension"/>
        <property name="preferredName"/>
        <property name="title"/>
        <many-to-one name="user" column="user_id"/>
        <joined-subclass name="PMSContact" table="PMSContact">
            <key column="CONTACT_ID"/>
            <many-to-one name="prospect" column="prospect_id" not-null="true"/>
        </joined-subclass>
    </class>
</hibernate-mapping>

<set name="contacts" cascade="all-delete-orphan" inverse="true" lazy="true">
    <key column="prospect_id"/>
    <one-to-many class="PMSContact" order-by"lastName asc"/>
</set>       

2004-03-19 13:57:45,765 [ERROR] util.JDBCExceptionReporter - could not initialize collection: [Prospect.contacts#1]
java.sql.SQLException: Column not found,  message from server: "Unknown column 'contacts0_.lastName' in 'order clause'"

      Criteria crit = session.createCriteria(PMSContact.class);
      crit.addOrder( Order.asc("lastName"));
      List PMSContacts = crit.list();

sort="natural"

sort="my.custom.ContactComparator"