Infragistics WPF XamDataGrid binding to a class property

I with to replace a WPF ListView control with an Infragistics WPF XamDataGrid.

 I am binding to a class Employee that includes a class property of type Address.  However, whilst the ListView has no problem binding to any property within the class (e.g. Address.Postcode), the XamDataGrid displays the Address class name and not the Address.Postcode property value

        <ListView
            <ListView.View>
                    <GridViewColumn DisplayMemberBinding="{Binding Surname}"
                    <GridViewColumn DisplayMemberBinding="{Binding Address.Postcode}" />

       <igDP:XamDataGrid >
            <igDP:XamDataGrid.FieldLayouts>
                <igDP:FieldLayout>
                             <igDP:Field Name="Surname"   >
                             <igDP:Field Name="Address.Postcode"   >


Where am I going wrong?