I create some unbound fields for my own fieldlayout.

...
 string[] strarray = { "aaa", "bbb", "ccc" };
 string[] cols = {"1","2","3"};
        Infragistics.Windows.DataPresenter.FieldLayout fl =
  new Infragistics.Windows.DataPresenter.FieldLayout();

 foreach (string name in cols)
 {
  CreateUnboundField(fl, name, name);
 }

 //CreateField(fl, "Value", "");

 this.SetGrid.FieldLayouts.Add(fl);

 this.SetGrid.DataSource = strarray;
...

CreateUnboundField and CreateField is like:

 public void CreateUnboundField(Infragistics.Windows.DataPresenter.FieldLayout fl, string name, string label)
 {
  Infragistics.Windows.DataPresenter.UnboundField codefield = new Infragistics.Windows.DataPresenter.UnboundField();
  codefield.Name = name;
  codefield.Label = label;
  fl.Fields.Add(codefield);
 }

        public void CreateField(Infragistics.Windows.DataPresenter.FieldLayout fl,string name,string label)
        {
            Infragistics.Windows.DataPresenter.Field codefield = new Infragistics.Windows.DataPresenter.Field();
            codefield.Name = name;
            codefield.Label = label;

            fl.Fields.Add(codefield);
        }

If I create a bound field in my fieldlayout, grid will change the default fieldlayout to one which just includes "Value" field.
What's the problem?  I use the 9.1 assembly.