[Data_Grid view] มีปัญหาการเรียก CommandField ภายใน Gridviews ครับ

<asp:CommandField UpdateText="Update" ItemStyle-HorizontalAlign="center" ItemStyle-Width="100px" ButtonType="Image"  ShowEditButton="true" CancelText="Cancel" DeleteText="Delete" EditText="Edit"  HeaderText="Action" EditImageUrl="../assets/images/edit-file.png" UpdateImageUrl="../assets/images/edit-file-success.png" CancelImageUrl="../assets/images/edit-file-cancel.png" />

protected void myGridView_RowCommand(object sender, GridViewCommandEventArgs e)
        {



            if (e.CommandName == "Update")
                {
                    SqlConnection conn = new SqlConnection("Server=192.168.0.4;PASSWORD=F@753951;database=ReportHR; User id=sa; ");
                    conn.Open();

                    TextBox log1 = (TextBox)myGridview.FindControl("lbProduct");
                    TextBox log2 = (TextBox)myGridview.FindControl("lbSeatsused");
                    TextBox log3 = (TextBox)myGridview.FindControl("lbSeatsavailable");
                    TextBox log4 = (TextBox)myGridview.FindControl("lbExpired");
                    TextBox log5 = (TextBox)myGridview.FindControl("lbOverdeployed");

                strSQL = "INSERT INTO log_activity (product,seatsused,seatsavailable,expired,overdeployed) " +
                " VALUES ('" + log1.Text + "','" + log2.Text + "','" + log3.Text + "' " +
                " ,'" + log4.Text + "','" + log5.Text + "')";

                SqlCommand comm = new SqlCommand(strSQL, conn);

                    

                    objCmd = new SqlCommand(strSQL, objConn);
                    objCmd.ExecuteNonQuery();

                    loadData();
                }
           
        }