Boton agregar error Object reference not set to an instance of an object

Question

Al darle el boton de agregar me manda ese error y no me agrega las filas seleccionadas del DGV

  private void Agregar()
{
    dataGridView1.AllowUserToAddRows = false;
    var rowsChecked = this.DataKitchenArea.AsEnumerable().Where(r => Convert.ToBoolean(r["Sel"]));

//    var dt = (DataTable)dataGridView1.DataSource;

    foreach (DataRow rowOrigen in rowsChecked)
    {
        DataRow rowDestino = this.DataTableSelection.NewRow();
        rowDestino["Sel"] = false;
        rowDestino["Id"] = rowOrigen["Id"];
        rowDestino["Nombre"] = rowOrigen["Nombre"];
        this.DataTableSelection.Rows.Add(rowDestino);
    }
    this.dataGridView1.DataSource = this.DataTableSelection;
     }