What am I doing wrong

//UnBound Field
UnboundField unBoundField = new UnboundField();
unBoundField.Label = "WFA";
Style stl = (Style)FindResource("UnBundcellStyle");
FieldSettings fieldSetting = new FieldSettings();
fieldSetting.CellValuePresenterStyle = stl;
unBoundField.Settings = fieldSetting;

//Regular Fieldse
Label lbl1 = new Label();
lbl1.Content = "Last Name";
Field field1 = new Field("LastName", lbl1);

Label lbl2 = new Label();
lbl2.Content = "First Name";
Field field2 = new Field("FirstName", lbl2);

Field field3 = new Field("IsEmployee");
field3.Visibility = Visibility.Collapsed;

FieldLayout fieldLayout = new FieldLayout();
fieldLayout.Fields.Add(unBoundField);
fieldLayout.Fields.Add(field1);
fieldLayout.Fields.Add(field2);
fieldLayout.Fields.Add(field3);

XamDataGrid TechGrid = new XamDataGrid();
TechGrid.FieldLayouts.Add(fieldLayout);