hello....i'm newbie developer.... i really need help at now... i just get started with Nhibernate thing at .Net... when i learn Inheritance and try it...it makes me confusing...why i get error like this : Initializing[AP.Core.Domain.AccountPayable.APInvoice#API03/04/2010/001]-Could not initialize proxy - no Session. this is my xml : <class xmlns="urn:nhibernate-mapping-2.2" mutable="true" name="AP.Core.Domain.AccountPayable.APAdjustment, AP.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" table="APAdjustment"> <id name="AdjustmentNumber" type="System.String, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <column name="AdjustmentNumber" length="17" /> <generator class="assigned" /> </id> <property name="Amount" type="System.Decimal, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <column name="Amount" /> </property> <property name="TransactionDate" type="System.DateTime, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"> <column name="TransactionDate" /> </property> <many-to-one class="AP.Core.Domain.AccountPayable.APInvoice, AP.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" lazy="proxy" name="PurchaseInvoice"> <column name="PurchaseInvoice_id" not-null="true" /> </many-to-one> <joined-subclass name="AP.Core.Domain.AccountPayable.APCreditAdjustment, AP.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null" lazy="true" table="APCreditAdjustment"> <key> <column name="APAdjustment_id" /> </key> </joined-subclass> </class> </hibernate-mapping> and this is inheritance Class : Parent Class -- public class APAdjustment { #region :FIELD private string adjustmentNumber; private decimal amount; private DateTime transactionDate; private APInvoice purchaseInvoice; Child Class -- public class APCreditAdjustment : APAdjustment { public APCreditAdjustment(){ and this my Data access : public IList<APAdjustment> GetByNameAll() { ICriteria criteria = Nhibernatesession.CreateCriteria(typeof(APAdjustment)); return criteria.List<APAdjustment>() ; } My Problem is : when i load data with gridview ...it works...but i change the property to autogenerate="true" ...i missing "PurchaseInvoice" field...and i change to bind manually,and it works..when i edit that gridview ...i get this error... Initializing[AP.Core.Domain.AccountPayable.APInvoice#API03/04/2010/001]-Could not initialize proxy - no Session so then i change my xml ...lazy="no-proxy" ...it still work...but when edit again ...i get error again ..and i do "Comment out the selected lines" to my association "Many-to-one"...i really works it..but that's not i want... CAN ANYBODY HELP ME...??Plizz...:( Note : I almost forget it ,i use fluent hibernate to generate to database.From fluent Hibernate ..i put *.xml file ...so i'm work to xml NHibernate...not fluent hibernate thing...:)