the differences of DataRelation class between 1.1 and 2.0

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

/**////<summary>
///Testtablerelation.
///</summary>
publicvoidRelation_1_1()
...{
DataTabledtParent=this.CreateDataTable();
dtParent.TableName="Parent";

DataRelationrelations=ds.Relations.Add("Relation",dtParent.Columns["index"],dtParent.Columns["parent_index"],false);

this.builder.Append(" GetthedatafromtreeROOT.");
this.GetLayerFromParent(ds,relations);
this.PrintDataTable(ds.Tables["parent"]);

this.builder.Append(" GetthedatafromtreeCHILDS.");
this.GetLayerFromChilds(ds,relations);
this.PrintDataTable(ds.Tables["parent"]);

this.DebugPrint(this.builder.ToString());
}

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:

/**////<summary>
///Testtablerelation.
///</summary>
publicvoidRelation_2_0()
...{
DataTabledtParent=this.CreateDataTable();
dtParent.TableName="Parent";

DataSetds=newDataSet();
ds.Tables.Add(dtParent);
DataRelationrelations=ds.Relations.Add("Relation",ds.Tables["Parent"].Columns["index"],ds.Tables["Parent"].Columns["parent_index"],false);

this.builder.Append(" GetthedatafromtreeROOT.");
this.GetLayerFromParent(ds,relations);
this.PrintDataTable(ds.Tables["parent"]);

this.builder.Append(" GetthedatafromtreeCHILDS.");
this.GetLayerFromChilds(ds,relations);
this.PrintDataTable(ds.Tables["parent"]);

this.DebugPrint(this.builder.ToString());

//this.WriteToTxtFile(this.builder.ToString());
}

what's your idea?