Are you trying to add new columns to your DataTable that is the grid''s DataSource? Or, are you trying to add unbound columns where the data does not come from the DataTable that is the grid''s DataSource?
Here is button handler code that does adds a column to an existing DataTable.
private void button1_Click(object sender, System.EventArgs e)
{
//dt is the grid''s DataSource
dt.Columns.Add("newcolumn");
this.gridDataBoundGrid1.Binder.InitializeColumns();
this.gridDataBoundGrid1.Refresh();
}
To use an unbound column, you add a GridBoundColumn with a name that is not a column in the DataSource. Then you handle QueryCellInfo and SaveCellInfo to provide and save teh unbound values for this column. This sample has unbound columns in it. \Syncfusion\Essential Studio\3.2.1.0\Windows\Grid.Windows\Samples\DataBound\GDBGMultiHeader
