What's wrong with mapping file.

I have next classes :

public class TechnoCardItem :
{
public virtual string Name
{
get;
set;
}

public virtual double Proporcion
{
get;
set;
}

public virtual double LowBound
{
get;
set;
}

public virtual double UpBound
{
get;
set;
}

public TechnoCardItem()
{
}

public TechnoCardItem(string element, double proporcion, double lowBound, double upBound)
{
this.Name = element;
this.Proporcion = proporcion;
this.LowBound = lowBound;
this.UpBound = upBound;
}
}

public class TechnoCardItemInput : TechnoCardItem
{
}

public class TechnoCardItemOutput : TechnoCardItem
{
}


public class TechnoCard
{
public string Name
{
get;
set;
}

public IList<TechnoCardItemInput> Input
{
get;
set;
}

public IList<TechnoCardItemOutput> Output
{
get;
set;
}

public TechnoCard()
{
ConstructorInits();
}

public TechnoCard(string Name)
{
this.Name = Name;
ConstructorInits();

}

private void ConstructorInits()
{
Input = new List<TechnoCardItemInput>();
Output = new List<TechnoCardItemOutput>();
}
}

and next mapping files for NHibernate :

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="DeliveryNoteHandler.Core.Domain.TechnoCard, DeliveryNoteHandler.Core" table="TechnoCards" lazy="false">

<id name="ID" column="TechnoCardID" unsaved-value="0">
<generator class="increment" />
</id>

<property name="Name" column="Name" />

<bag name="Input" cascade="all" inverse="true">
<key column="TechnoCardID" />
<one-to-many class="DeliveryNoteHandler.Core.Domain.TechnoCardItemInput, DeliveryNoteHandler.Core" />
</bag>

<bag name="Output" cascade="all" inverse="true">
<key column="TechnoCardID" />
<one-to-many class="DeliveryNoteHandler.Core.Domain.TechnoCardItemOutput, DeliveryNoteHandler.Core" />
</bag>

</class>
</hibernate-mapping>



<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="DeliveryNoteHandler.Core.Domain.TechnoCardItem, DeliveryNoteHandler.Core" table="TechnoCardItems" lazy="false">

<id name="ID" column="TechnoCardItemID" unsaved-value="0">
<generator class="increment" />
</id>

<discriminator column ="Flag" type="String" />
<property name="Name" column="Name" />
<property name="Proporcion" column="Proporcion" />
<property name="LowBound" column="LowBound" />
<property name="UpBound" column="UpBound" />
<subclass name="DeliveryNoteHandler.Core.Domain.TechnoCardItemInput, DeliveryNoteHandler.Core" discriminator-value="0" />
<subclass name="DeliveryNoteHandler.Core.Domain.TechnoCardItemOutput, DeliveryNoteHandler.Core" discriminator-value="1" />

</class>
</hibernate-mapping>

The problem is when I create TechnoCard from dataBase, element Flag in database is not compered with "0" or "1" and every item goes to Input list.