>Thanks for writing. Add Child also tries to reflect all available datasources and their schema, so it's possible that the problem is not related directly to ObjectDataSource.

You may be on to something there. In my case I was trying to bind the control to a class method that returns a dataset. The dataset contains three levels in its hierarchy. The top level is a list of aircraft tail numbers. The second level is a list of maintenance tasks performed on the aircraft. The first and second levels are related by the tail number field. The third level is a list of parts used during the maintenance task. The second and third levels are related by a unique tracking number assigned to each maintenance task. The entire dataset is built in the class and a call to the class method returns the dataset. I wonder if the problem has to do with the fact that the dataset is not created until runtime?

If you paste here the datatasources you have on the page (or directly the whole ASPX syntax) plus some additional information about your ObjectDataSource - we will do my best to reproduce and address the problem.

Below is a sample class and webform that demonstrates the problem.

Imports System.Data

Public Class foo

    Public Shared Function GetData() As DataSet
        Dim DS As New DataSet("Testing")
        Dim dtTailNumber As New DataTable("TailNumber")
        Dim DC As DataColumn
        DC = New DataColumn("TailNumber")
        DC.DataType = GetType(String)
        DC.ColumnName = "TailNumber"
        dtTailNumber.Columns.Add(DC)
        DS.Tables.Add(dtTailNumber)

        'Maintenance List
        Dim dtMAN As New DataTable("MAN")
        DC = New DataColumn("TailNumber")
        DC.DataType = GetType(String)
        dtMAN.Columns.Add(DC)
        DC = New DataColumn("MAN#")
        DC.DataType = GetType(String)
        dtMAN.Columns.Add("MAN#")
        DS.Tables.Add(dtMAN)

        'Parts List
        Dim dtParts As New DataTable("Parts")
        DC = New DataColumn("MAN#")
        DC.DataType = GetType(String)
        dtParts.Columns.Add(DC)
        DC = New DataColumn("PartNumber")
        DC.DataType = GetType(String)
        dtParts.Columns.Add(DC)
        DS.Tables.Add(dtParts)

        'Create Relationships
        Dim DataRel As DataRelation
        Dim ParentCol As DataColumn
        Dim ChildCol As DataColumn
        'Tail Numbers
        ParentCol = DS.Tables("TailNumber").Columns("TailNumber")
        ChildCol = DS.Tables("MAN").Columns("TailNumber")
        DataRel = New DataRelation("TailNumber", ParentCol, ChildCol)
        DS.Relations.Add(DataRel)

        'Repair Actions
        ParentCol = DS.Tables("Parts").Columns("MAN#")
        ChildCol = DS.Tables("Parts").Columns("MAN#")
        DataRel = New DataRelation("MANNumber", ParentCol, ChildCol)
        DS.Relations.Add(DataRel)

        Return DS
    End Function

End Class

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default3.aspx.vb" Inherits="Default3" %>

<%@ Register Assembly="Infragistics2.Web.Preview.v8.1, Version=8.1.20081.1000, Culture=neutral, PublicKeyToken=7dd5c3163f2cd0cb"
    Namespace="Infragistics.Web.UI.WebControls" TagPrefix="cc1" %>