Hi,
I am new to NHibernate and am having some major difficulties.
I am using a WCF hosting application developed by another developer in my organisation.
The problem I am having is when I try to send my populated object across the wire I get "Object reference not set to an instance of an object".
A little about my class structure:
I have a class design for patient data.
It is made up of many Collection properties e.g. IList<PatientAddress> patientAddresses, IList<PatientIdentifier> patientIdentifiers and so on. If I populate one of the ILists it works fine, but when I attempt to populate more than one I get the above error.

My Configuration File looks like this

<?xml version="1.0" encoding="utf-8" ?>
<!-- Maps to the Patient Domain Object -->
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="NISG.Framework.PatientModule.Domain.Classes.Patient, NISG.Framework.PatientModule.Domain" table="tbl_patients" lazy="false">
<id name="Id"
type="System.Guid"
unsaved-value="00000000-0000-0000-0000-000000000000"
column="patient_id">
<generator class="guid.comb"/>
</id>
<property name="DateOfBirth" column="date_of_birth"/>
<property name="DateOfDeath" column="date_of_death"/>
<property name="GenderAtBirth" column="gender_at_birth"/>
<property name="MaritalStatus" column="marital_status"/>
<property name ="CurrentGender" column="current_gender"/>

<bag name="Names" cascade="all">
<key column="patient_id"/>
<one-to-many class="NISG.Framework.PatientModule.Domain.Classes.PatientName, NISG.Framework.PatientModule.Domain"/>
</bag>

<bag name="Addresses" cascade="all">
<key column="patient_id"/>
<one-to-many class="NISG.Framework.PatientModule.Domain.Classes.PatientAddress, NISG.Framework.PatientModule.Domain"/>
</bag>
<bag name="PatientIdentifiers" cascade="all">
<key column="patient_id"/>
<one-to-many class="NISG.Framework.PatientModule.Domain.Classes.PatientIdentifier, NISG.Framework.PatientModule.Domain"/>
</bag>
<bag name="AssociatedPeople" cascade="all">
<key column="patient_id"/>
<one-to-many class="NISG.Framework.PatientModule.Domain.Classes.AssociatedPerson, NISG.Framework.PatientModule.Domain"/>
</bag>
<bag name="TelephoneNumbers" cascade="all">
<key column="patient_id"/>
<one-to-many class="NISG.Framework.PatientModule.Domain.Classes.PatientTelephoneNumber, NISG.Framework.PatientModule.Domain"/>
</bag>
<bag name="EletronicContacts" cascade="all">
<key column="patient_id"/>
<one-to-many class="NISG.Framework.PatientModule.Domain.Classes.PatientElectronicContact, NISG.Framework.PatientModule.Domain"/>
</bag>
</class>
</hibernate-mapping>
Please Help...
my head is sore from the repeated battering on the wall...
Cheers,
Mark