DATAGRIDVIEW中CHECKBOX选后行的值相加问题

C# code

        private void NOPAY_CellClick(object sender, DataGridViewCellEventArgs e)        {            double c = 0;            if (e.ColumnIndex == 0)            {                for (int i = 0; i < this.NOPAY.RowCount; i++)                {                    if (this.NOPAY.Rows[i].Cells[0].Value.ToString () == "1")                    {                        c += double.Parse(this.NOPAY[4, i].Value.ToString());                        this.label5.Text = c.ToString();                    }                }            }        }

第一列是CHECKBOX,想点一下CHECKBOX,将第四列的值相加.提示if (this.NOPAY.Rows[i].Cells[0].Value.ToString () == "1")
这句有错,具体要什么搞啊,请高手帮帮我

[解决办法]

C# code

for (int i = 0; i <= gvlistdetailauChoix.Rows.Count - 1; i++)            {                CheckBox cbox = (CheckBox)gvlistdetailauChoix.Rows[i].FindControl("cbNumerolist");                if (cbox.Checked == true)                {                    listnumero.Add(gvlistdetailauChoix.Rows[i].Cells[1].Text);                    listnom.Add(gvlistdetailauChoix.Rows[i].Cells[2].Text);                }            }