I'm building a web application in Visual studio .net 2008, using Nhibernate.

I cant not remove an item from a bag(list).

I have this definition:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Seguimiento.Bussiness" namespace="Seguimiento.Bussiness.Entities" default-access="field.camelcase-underscore" >

<class name="DetallesPj" table="detalles_PJ">

<id name="ClienteKey" column="cliente_id" type="Int32" unsaved-value="0">
<generator class="foreign">
<param name="property">Cliente</param>
</generator>
</id>
<one-to-one name="Cliente" class="Cliente" constrained="true"/>
<bag name="ContactoList" cascade="all" inverse="true">
<key column="cliente_id" />
<one-to-many class="Contacto" />
</bag>
<property column="nombre" type="String" name="Nombre" not-null="true" length="256" />
<property column="gerente_general" type="String" name="GerenteGeneral" length="256" />
<property column="direccion" type="String" name="Direccion" length="1024" />
<many-to-one name="Actividad" column="actividad_id" class="Actividad" />
<property column="web_address" type="String" name="WebAddress" length="1024" />
<property column="numero_empresas" type="Int32" name="NumeroEmpresas" />
<property column="cedula_persona_juridica" type="String" name="CedulaPersonaJuridica" not-null="true" length="20" />
<property column="telefono" type="String" name="Telefono" length="20" />
<property column="fax" type="String" name="Fax" length="20" />
<property column="email" type="String" name="Email" length="256" />
<many-to-one name="Area" column="area_id" class="Area" />

</class>

</hibernate-mapping>

this bag holds a list f contact wich i show in a repeater y my page, repaeater definition is like this:

<td colspan="2">
<div class="scroller" style="height: 80px; width: 100%" >
<asp:Repeater ID="rptContactos" runat="server" OnItemCommand="rptContactos_ItemCommand">

<HeaderTemplate>
<table width="100%" border="0" cellpadding="0" cellspacing="1" bgcolor="#86b1c3" >
</HeaderTemplate>
<ItemTemplate>
<asp:HiddenField ID="h_ContactKey" runat="server" Value='<%# Eval("Contacto")%>' />
<tr id="trContacto" runat="server" class="rowOut" onmouseout="if(this.className!='rowSelected')this.className='rowOut'" onmouseover="if(this.className!='rowSelected')this.className='rowOver'">
<td align="center" nowrap="nowrap" width="10">
<asp:LinkButton ForeColor="#000000" ID="link1" runat="server" Width="100%" CommandArgument='<%# Eval("Contacto") %>'>
<img id="imgCheck" style="border: 0px; margin-right: 5px" runat="server" alt="Proyecto Seleccionado" src="../images/check.gif" visible="False" /><%# Eval("Contacto")%></asp:LinkButton>
</td>
<td align="left" nowrap="nowrap" width="90px" >
<asp:LinkButton ForeColor="#000000" ID="lblCedulaentidad" runat="server" Width="100%" CommandArgument='<%# Eval("Contacto")%>'><%# Eval("Cedulaentidad")%></asp:LinkButton></td>
<td align="left" nowrap="nowrap">
<asp:LinkButton ForeColor="#000000" ID="lblNombre" runat="server" Width="100%" CommandArgument='<%# Eval("Contacto")%>'><%# Eval("Nombre")%></asp:LinkButton>
</td>
</tr>
</ItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>
</div>
</td>

and this button defined to eliminate an item of contactlist and this is the code wrote for this:

int selCliente = Convert.ToInt32(h_selectedCliente.Value);
Cliente cli = ClienteFactory.GetById(selCliente);
int contId = Convert.ToInt32(h_ContactKey.Value);
Contacto DelContacto = ContactoFactory.GetById(contId);
cli.DetallesPj.ContactoList.Remove(DelContacto);

and it seem to be ok first time, but the second time i try to remove an element I get the first element erased back in the list and, so for me was never erased.

Can someone tell me why is this why can it be removed?
thank's