trying to total gridview in asp - asp.net

Question

i am trying to total the price and quantity of all the products added to the gridview and i can't seem to figure out why the total is not showing in the footer. the code that i have for the vb should multiply the quantity with the price and put it into the footer of the gridview. the gridview footer is visible so i know that's not the problem. any help would be appreciated.
asp:
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataSourceID="Cart" AllowSorting="True" BackColor="White"
BorderColor="#999999" BorderStyle="None" BorderWidth="1px" CellPadding="3"
GridLines="Vertical" ShowFooter="True" AutoGenerateEditButton="True"
AutoGenerateDeleteButton="True" DataKeyNames="cartID">
<AlternatingRowStyle BackColor="Gainsboro" />
<Columns>
<asp:BoundField DataField="cartID" HeaderText="cartID" SortExpression="cartID"
InsertVisible="False" ReadOnly="True" Visible="False"></asp:BoundField>
<asp:BoundField DataField="cartNO" HeaderText="cartNO" SortExpression="cartNO"
Visible="False" />
<asp:BoundField DataField="productID" HeaderText="productID"
SortExpression="productID" InsertVisible="False" ReadOnly="True" />
<asp:BoundField DataField="productName" HeaderText="productName"
SortExpression="productName" InsertVisible="False" ReadOnly="True" />
<asp:BoundField DataField="price" HeaderText="price"
SortExpression="price" InsertVisible="False" ReadOnly="True" />
<asp:BoundField DataField="quantity" HeaderText="quantity"
SortExpression="quantity" />
<asp:TemplateField HeaderText="SubTotal" SortExpression="subTotal" >
<ItemTemplate>
<%# Eval("price") * Eval("quantity")%>
</ItemTemplate>
<%-- <FooterTemplate>
<asp:Label ID="sum" runat="server"/>
</FooterTemplate>--%>
</asp:TemplateField>
VB
Public Class MyCart
Inherits System.Web.UI.Page
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim strcartNO As String = ""
Dim cookieBack As HttpCookie
cookieBack = HttpContext.Current.Request.Cookies("cartNO")
strcartNO = cookieBack.Value
'sqldscartLine.selectCommand = "Select * from cartLine where cartNO = '" & strcartNO & "'"
GridView1.DataBind()
End Sub
Public Shared Sub DeleteMethod(ByVal original_OrderID As Integer, _
ByVal original_ProductID As Integer)
End Sub
Dim priceTotal As Decimal = 0
Dim quantityTotal As Integer = 0
Sub GridView1_RowDataBound(ByVal sender As Object, _
ByVal e As GridViewRowEventArgs)
If e.Row.RowType = DataControlRowType.DataRow Then
' add the UnitPrice and QuantityTotal to the running total variables
priceTotal += Convert.ToDecimal(DataBinder.Eval(e.Row.DataItem, _
"price"))
quantityTotal += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, _
"quantity"))
ElseIf e.Row.RowType = DataControlRowType.Footer Then
e.Row.Cells(2).Text = "Totals:"
' for the Footer, display the running totals
e.Row.Cells(3).Text = priceTotal.ToString("c")
e.Row.Cells(4).Text = quantityTotal.ToString("d")
e.Row.Cells(3).HorizontalAlign = HorizontalAlign.Right
e.Row.Cells(4).HorizontalAlign = HorizontalAlign.Right
e.Row.Font.Bold = True
End If
End Sub

Answer 1

Not sure if anybody saw the comment, so will put it in an answer instead - This might help others out (if I'm correct..)
Your code has the following in
<%-- <FooterTemplate>
<asp:Label ID="sum" runat="server"/>
</FooterTemplate>--%>
The <%-- and --%> are comments, so your footer is being commented out.
Change it to
<FooterTemplate>
<asp:Label ID="sum" runat="server"/>
</FooterTemplate>
And it should display.

Answer 2

Databinding creates data rows. The footer isn't a data row, so the event RowDataBound is not called when it's created. Thus, your event handler GridView1_RowDataBound will never execute the code that generates the totals, since the expression
e.Row.RowType = DataControlRowType.Footer
... will never be true during any execution of that method.
Try handling the RowCreated event instead, like so:
Sub GridView1_RowCreated(ByVal sender As Object, _
ByVal e As GridViewRowEventArgs)
If e.Row.RowType = DataControlRowType.Footer Then
e.Row.Cells(2).Text = "Totals:"
' for the Footer, display the running totals
e.Row.Cells(3).Text = priceTotal.ToString("c")
e.Row.Cells(4).Text = quantityTotal.ToString("d")
e.Row.Cells(3).HorizontalAlign = HorizontalAlign.Right
e.Row.Cells(4).HorizontalAlign = HorizontalAlign.Right
e.Row.Font.Bold = True
End If
End Sub