C1flexgrid 中居然不显示节点的连线？

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在Load方法中
private void Form1_Load(object sender, EventArgs e)
      {

c1FlexGrid1.AddItem(new object[] { "Test"});
                  C1.Win.C1FlexGrid.Row row = c1FlexGrid1.Rows[c1FlexGrid1.Rows.Count - 1];
                  row.IsNode = true;
                  row.Style = c1FlexGrid1.Styles["Node"];
                  row.Node.Level= 0;

                  c1FlexGrid1.AddItem(new object[] { "test" });
                  row= c1FlexGrid1.Rows[c1FlexGrid1.Rows.Count - 1];
                  row.IsNode = true;
                  row.Style = c1FlexGrid1.Styles["Node"];
                  Node nd1 = row.Node;
                  nd1.Level = 1;

},显示确没有节点间的关系连结线，请问如何处理，谢谢！