ค่าจาก Texbox To Datagridview ไม่ยอมส่งค่า ค่ะ เป็น Nothing

<asp:DataList ID="DataList1" runat="server" 
            RepeatColumns="1" Width="393px">
            <HeaderTemplate>รายละเอียดสินค้า</HeaderTemplate>
            <ItemTemplate>
                <asp:Table ID="Table1" runat="server">
                    <asp:TableHeaderRow><asp:TableCell RowSpan="8"><asp:Image ID="imgProduct" runat="server" ImageUrl='<%# GetImagePath(Eval("Cake_picture").ToString())%>' /></asp:TableCell></asp:TableHeaderRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">รหัสสินค้า :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:Label ID="lblProductID" runat="server" Text='<%#Eval("Cake_id") %>'></asp:Label></asp:TableCell>
                    </asp:TableRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">ชื่อสินค้า :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:Label ID="Label2" runat="server" Text='<%#Eval("Cake_Name") %>'></asp:Label></asp:TableCell>
                    </asp:TableRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">รายละเอียดสินค้า :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:Label ID="Label3" runat="server" Text='<%#Eval("Cake_detail") %>'></asp:Label></asp:TableCell>
                    </asp:TableRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">ราคาสินค้า :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:Label ID="lblPrice" runat="server" Text='<%#Eval("Cake_price") %>'></asp:Label></asp:TableCell>
                    </asp:TableRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">ส่วนลดสินค้า :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:Label ID="lblDiscount" runat="server" Text='10'></asp:Label>%</asp:TableCell>
                    </asp:TableRow>
                    
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">ระบุจำนวน :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:TextBox ID="txtQty" runat="server" Width="50px"></asp:TextBox></asp:TableCell>
                    </asp:TableRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px">ระบุขนาดเค้ก :</asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><asp:TextBox ID="txtPound" runat="server" Width="50px"></asp:TextBox></asp:TableCell>
                    </asp:TableRow>
                    <asp:TableRow>
                    <asp:TableCell HorizontalAlign="Right" Width="100px"></asp:TableCell>
                    <asp:TableCell HorizontalAlign="Left" Width="100px"><a href="VeiwProductDetail.aspx?proc=<%#Eval("Cake_id") %>">หยิบใส่ตระกร้า</a></asp:TableCell>
                    </asp:TableRow>
                </asp:Table>
            
            </ItemTemplate>
            
        </asp:DataList>

Protected Sub DataList1_ItemDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataListItemEventArgs) Handles DataList1.ItemDataBound
        Dim txtQty As TextBox = CType(e.Item.FindControl("txtQty"), TextBox)
        For i As Integer = 0 To DataList1.Items.Count - 1
            txtQty = DataList1.Items(i).FindControl("txtQty")
        Next

    End Sub