NHibernate version: 1.2.0.1001

I have a class:"Automobile" which has a property:"Drivers" that I would like to return an instance of a DriverCollection class. DriverCollection inherits System.Collections.Collectionbase and implements IList. (I have done this because the documentation, and examples, seem to indicate that the property:"Drivers" should return an IList. (when using a bag)

I am able to persist Automobile if Drivers returns IList, but not DriverCollection. Why is this the case if DriverCollection implements IList?

Here's a mapping example:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.0" assembly="myPersistenceApp" namespace="myPersistenceApp">
<class name="Car" table="Automobiles">

<id name="SerialNum" column="SerialNum" type="int">
<generator class="assigned"/>
</id>

<bag name="Drivers" table="driverLookup" lazy="true">
<key column="serialNum"/>
<one-to-many class="Driver"/>
</bag>

<property column="color" type="String" name="Color" />
<property column="speed" type="int" name="Speed" />
<property column="weight" type="int" name="Weight" />

</class>
</hibernate-mapping>

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This has to do with NHibernate's use of proxies. You can only accurately use the interface. However you can use a generic collection, IList<Driver>, or you can have DriverCollection act as a wrapper around IList like this: