Gridview Control ไม่สามารถ Delete Update ได้ค่ะ รบกวนพี่ๆช่วยดูโค้ดให้ทีค่ะ

protected void GridViewBindData()
        {
            SqlConnection Conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["InsuranceConnectionString"].ConnectionString);
            Conn.Open();
            string str = "SELECT i.InsuranceF_id,i.Form_id,i.credit,i.Customer_id,i.date,i.Employee_id,f.Form_id,f.formname,c.Customer_id,c.name,c.surname FROM InsuranceF i,Customer c,Form f WHERE i.Customer_id = c.Customer_id AND i.Form_id=f.Form_id AND i.Employee_id ='" + Session["Employee_id"] + "' AND name LIKE '%" + Keyword + "%'";
            SqlDataReader dtReader;
            SqlCommand command = new SqlCommand(str, Conn);
            dtReader = command.ExecuteReader();
            GridView1.DataSource = dtReader;
            GridView1.DataBind();

            dtReader.Close();
            dtReader = null;
            Conn.Close();
        }

        public DataTable DataTableFormname()
        {
            SqlConnection Conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["InsuranceConnectionString"].ConnectionString);
            Conn.Open();
            SqlDataAdapter dtAdapter = new SqlDataAdapter();
            DataTable dt = new DataTable();
            string str = "SELECT * FROM Form";

            dtAdapter = new SqlDataAdapter(str, Conn);
            dtAdapter.Fill(dt);

            dtAdapter = null;

            return dt;
            Conn.Close();
        }

        protected void modEditCommand(object sender, GridViewEditEventArgs e)
        {
            GridView1.EditIndex = e.NewEditIndex;
            GridViewBindData();
        }

        protected void modCancelCommand(object sender, GridViewCancelEditEventArgs e)
        {
            GridView1.EditIndex = -1;
            GridViewBindData();
        }

        protected void modDeleteCommnad(object sender, GridViewDeletedEventArgs e)
        {
            SqlConnection Conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["InsuranceConnectionString"].ConnectionString);
            Conn.Open();
            string str = "DELETE FROM InsuranceF WHERE InsuranceF_id ='" + GridView1.DataKeys[e.RowIndex].Value + "'";
            SqlCommand command = new SqlCommand(str, Conn);
            command.ExecuteNonQuery();
            GridView1.EditIndex = -1;
            GridViewBindData();
        }

        protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow)
            {
                TextBox txtdate = (TextBox)e.Row.FindControl("txtdate");
                if (txtdate != null)
                {
                    txtdate.Text = (string)DataBinder.Eval(e.Row.DataItem, "date");
                }
                TextBox txtcredit = (TextBox)e.Row.FindControl("txtcredit");
                if (txtcredit != null)
                {
                    txtcredit.Text = (string)DataBinder.Eval(e.Row.DataItem, "credit");
                }
                DropDownList ddlformname = (DropDownList)e.Row.FindControl("ddlformname");
                if (ddlformname != null)
                {
                    ddlformname.DataSource = (DataTable)DataTableFormname();
                    ddlformname.DataTextField = "formname";
                    ddlformname.DataValueField = "Form_id";
                    ddlformname.DataBind();
                    ddlformname.Items.IndexOf(ddlformname.Items.FindByValue((string)DataBinder.Eval(e.Row.DataItem, "Form_id")));
                }
            }
        }

        protected void modUpdateCommand(Object sender, GridViewUpdatedEventArgs e)
        {
            TextBox txtdate = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txtdate");
            TextBox txtcredit = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txtcredit");
            DropDownList ddlformname = (DropDownList)GridView1.Rows[e.RowIndex].FindControl("ddlformname");

            SqlConnection Conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["InsuranceConnectionString"].ConnectionString);
            Conn.Open();
            string str = "UPDATE InsuranceF SET credit = '" + txtcredit.Text + "',date = '" + txtdate.Text + "',Form_id = '" + ddlformname.SelectedItem.Value + "' WHERE InsuranceF_id ='" + GridView1.DataKeys[e.RowIndex].Value + "'";
            SqlCommand command = new SqlCommand(str, Conn);
            command.ExecuteNonQuery();
            GridView1.EditIndex = -1;
            GridViewBindData();
        }

<!--gridview-->
            <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" DataKeyNames="InsuranceF_id"
            onRowDataBound="GridView1_RowDataBound"
            OnRowEditing="modEditCommand"
            OnRowCancelingEdit="modCancelCommand"
            OnRowDeleting="modDeleteCommand"
            OnRowUpdating="modUpdateCommnad">
             
             <Columns>
            
                <asp:TemplateField HeaderText="InsuranceF_id" Visible="false">
                    <ItemTemplate>
                        <asp:Label ID="lblInsuranceF_id" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.InsuranceF_id") %>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:Label ID="lblInsuranceF_id" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.InsuranceF_id") %>'></asp:Label>
                    </EditItemTemplate>
                </asp:TemplateField>
                
                <asp:TemplateField HeaderText="ชื่อ">
                    <ItemTemplate>
                        <asp:Label ID="name" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.name") %>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:Label ID="lblname" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.name") %>'></asp:Label>
                    </EditItemTemplate>
                </asp:TemplateField>
                
                <asp:TemplateField HeaderText="นามสกุล">
                    <ItemTemplate>
                        <asp:Label ID="surname" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.surname") %>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:Label ID="lblsurname" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.surname") %>'></asp:Label>
                    </EditItemTemplate>
                </asp:TemplateField>
                
                <asp:TemplateField HeaderText="แบบประกัน">
                    <ItemTemplate>
                        <asp:Label ID="formname" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.formname") %>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:DropDownList ID="ddlformname" runat="server"></asp:DropDownList>
                    </EditItemTemplate>
                </asp:TemplateField>
                
                <asp:TemplateField HeaderText="ยอดเงิน">
                    <ItemTemplate>
                        <asp:Label ID="credit" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.credit") %>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:TextBox ID="txtcredit" runat="server"></asp:TextBox>
                    </EditItemTemplate>
                </asp:TemplateField>
                
                <asp:TemplateField HeaderText="วันที่ขาย">
                    <ItemTemplate>
                        <asp:Label ID="date" runat="server" Text='<%# DataBinder.Eval(Container,"DataItem.date") %>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:TextBox ID="txtdate" runat="server"></asp:TextBox>
                    </EditItemTemplate>
                </asp:TemplateField>
                
                <asp:CommandField HeaderText="" ShowEditButton="true" CancelText="Cancel" DeleteText="Delete" EditText="Edit" UpdateText="Update" />
                <asp:CommandField ShowDeleteButton="true" HeaderText="" />
            </Columns>
            
            </asp:GridView>
        <!--endgridview-->