Updating a datagrid

[Rocketdawg]

I'm overlooking the obvious again...

I've got a page for products. When I press 'add to cart' on that page, it updates a data table held in session and redirects to a 'my cart' page.

Here's the Load for the 'my cart'

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        
        objCartDT = Session("Cart")
        If objCartDT Is Nothing Then
            lblNoItems.Text = "There are no items in your cart."
        Else
            lblTotal.Text = "Total: $" & GetItemTotal()
            dgCart.DataSource = Session("Cart")
            dgCart.DataBind()
        End If
    End Sub

If they want to change a quantity, I've got this sub on the page:

Sub dgCart_Update(ByVal s As Object, ByVal e As DataGridCommandEventArgs)
        Dim txtQuantity As TextBox
        Dim intCartID As Integer
        intCartID = dgCart.DataKeys(e.Item.ItemIndex)
        txtQuantity = e.Item.FindControl("txtQuantity")
 
        For Each objDR In objCartDT.Rows
            If objDR("CartID") = intCartID Then 'this validates true
                objDR("Quantity") = Int32.Parse(txtQuantity.Text)
                Exit For
            End If
        Next
 
        lblTotal.Text = "Total: $" & GetItemTotal()
        dgCart.EditItemIndex = -1
        dgCart.DataSource = objCartDT
        dgCart.DataBind()
    End Sub

I don't throw any errors, but I don't update the cart either . Not exactly sure where I'm screwing this up....any help?

Thanks