if add row to DataTable
DataRow row = datatable1.NewRow();
row[\"column2\"]=\"column2\";
row[\"column6\"]=\"column6\";
datatable1.Rows.Add(row);
This is how I add a row if the dgrview is empty: (myDataGridView has two columns in my example)
DataGridViewRow row = new DataGridViewRow();
row.CreateCells(myDataGridView);
row.Cells[0].Value = "some value";
row.Cells[1].Value = "next columns value";
myDataGridView.Rows.Add(row);
According to docs: "CreateCells() clears the existing cells and sets their template according to the supplied DataGridView template".