How to reproduce:
DataTable table = new DataTable();
table.Columns.Add("ParentId", typeof(int));
table.Columns.Add("ChildId", typeof(int));
table.Columns.Add("ProductId", typeof(int));
table.Columns.Add("ProductCode", typeof(string));
table.Rows.Add(0, 1, 3, "Pr - 01");
table.Rows.Add(1, 2, 4, "P r- 02");
table.Rows.Add(1, 3, 5, "Pr - 03");
this.radTreeView1.DisplayMember = "ProductCode";
this.radTreeView1.ParentMember = "ParentId";
this.radTreeView1.ChildMember = "ChildId";
this.radTreeView1.ValueMember = "ProductId";
this.radTreeView1.DataSource = table;