why we get empty string in string cid = row.Cells[1].Text;

public void chkStatus_OnCheckedChanged(object sender, EventArgs e)
    {
        CheckBox chkStatus = (CheckBox)sender;
        //GridViewRow row = (GridViewRow)chkStatus.NamingContainer;
        GridViewRow row = (GridViewRow)chkStatus.NamingContainer;


        string cid = row.Cells[1].Text;
        bool status = chkStatus.Checked;

        //ITWLTD-DEV01



        ////string constr = @"Server=.\SQLEXPRESS;Database=TestDB;uid=waqas;pwd=sql;";
        //string constr = @"Server=ITWLTD-DEV01;Database=property;Integrated Security=true;";
        //string query = "UPDATE marketing SET Approved = @Approved WHERE id = @id";

        //SqlConnection con = new SqlConnection(constr);
        //// SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["cn"].ConnectionString);
        //SqlCommand com = new SqlCommand(query, con);

        ////Convert.ToInt32(eInfo.isActive)
        //// Convert.ToBoolean(dataReader["isActive"]);



        string constr = @"Server=ITWLTD-DEV01;Database=property;Integrated Security=true;";
        string query = "UPDATE market SET Approved = @Approved WHERE id = @id";

        SqlConnection con = new SqlConnection(constr);
        SqlCommand com = new SqlCommand(query, con);




        com.Parameters.Add("@Approved", SqlDbType.Bit).Value = status;
        com.Parameters.Add("@id", Convert.ToInt32(SqlDbType.Int)).Value = cid;

        //com.Parameters.Add("@id", SqlDbType.Int).Value = cid;


        con.Open();
        com.ExecuteNonQuery();
        con.Close();

        // LoadData();
        BindData();
    }