Bolitto:
Sorry this waited so long for a reply!
It sounds like you were trying either to use the BindingNavigatorAddNewItem button on a BindingNavigator without first configuring it properly, or that you were trying to add to a ReadOnlyEntityList, which is the type of list we always return from navigation properties (like myEmployee.Orders).
Please have a look at the instructional unit "Adding and Deleting Business Objects" (100 series); also see the document "AddDeleteWithBindingNavigator.DOC" in the Reference Materials folders of the instructional unit "Add-Delete On Child Grid" (200 series).
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Best regards,
Greg Dunn
IdeaBlade