please review this and also read comment it might help you.
public void CreateDatatableofSelectedRows()
{
DataTable _selectedRows = new DataTable();
_selectedRows.Columns.Add("Name");
DataRow _dr;
foreach (GridViewRow gvr in this.gridISSControl.Rows)
{
if (((System.Web.UI.WebControls.CheckBox)gvr.FindControl("chkSelect")).Checked == true)
{
_dr = _selectedRows.NewRow();
_dr["Name"] = gvr.Cells[1].Text;
_selectedRows.Rows.Add(_dr);
}
}
_selectedRows.AcceptChanges();
}