Listbox Items Not Visible after Databind from DataTable

Hi All,
I am in the process of writing a type of shopping cart, to be used to select parts from a database table via a gridview displaying search results.  The search functionality works great.  I included a textbox as a template field so that users can input the quantity of each item the want quoted.  My code-behind file writes the gridview values to a databtable and is supposed to databind to a listbox.  However, when I run the page in browser, the listbox items are selectable but not visible.  Here's my code:
1.  Code Behind:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 'Define DataTable Columns as incoming gridview fields Dim dtSelParts As DataTable = New DataTable Dim dr As DataRow = dtSelParts.NewRow() dtSelParts.Columns.Add("PartNumber") dtSelParts.Columns.Add(& ...