when u use the follow code on 1.1.it will compile without error.

when u use the follow code on 1.1.it will compile without error. 

Code
 1 /**//**//**//// <summary>
 2        /// Test table relation.
 3        /// </summary>
 4        public void Relation_1_1()
 5        {
 6            DataTable dtParent = this.CreateDataTable();
 7            dtParent.TableName = "Parent";
 8
 9            DataRelation relations = ds.Relations.Add("Relation", dtParent.Columns["index"], dtParent.Columns["parent_index"], false);
10
11            this.builder.Append(" Get the data from tree ROOT.");
12            this.GetLayerFromParent(ds, relations);
13            this.PrintDataTable(ds.Tables["parent"]);
14
15            this.builder.Append(" Get the data from tree CHILDS.");
16            this.GetLayerFromChilds(ds, relations);
17            this.PrintDataTable(ds.Tables["parent"]);
18
19            this.DebugPrint(this.builder.ToString());
20        }

while it will run error on 2.0 with "Cannot create a DataRelation if Parent or Child Columns are not in a DataSet.".

if u want to run normally,u can use this cod:

Code
 1**/**///// <summary>
 2        /// Test table relation.
 3        /// </summary>
 4        public void Relation_2_0()
 5        {
 6            DataTable dtParent = this.CreateDataTable();
 7            dtParent.TableName = "Parent";
 8
 9            DataSet ds = new DataSet();
10            ds.Tables.Add(dtParent);
11            DataRelation relations = ds.Relations.Add("Relation", ds.Tables["Parent"].Columns["index"], ds.Tables["Parent"].Columns["parent_index"], false);
12
13            this.builder.Append(" Get the data from tree ROOT.");
14            this.GetLayerFromParent(ds, relations);
15            this.PrintDataTable(ds.Tables["parent"]);
16
17            this.builder.Append(" Get the data from tree CHILDS.");
18            this.GetLayerFromChilds(ds, relations);
19            this.PrintDataTable(ds.Tables["parent"]);
20
21            this.DebugPrint(this.builder.ToString());
22            
23            //this.WriteToTxtFile(this.builder.ToString());
24        }