Autocomplete Extender Problem

I am having a problem getting an autocomplete extender to work in asp.net.  Below is the code that I am attempting as a test to get it working.  Currently, nothing happens when text is entered into the text box.:

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Autocomplete.asmx:
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<%@ WebService Language="VB" Class="Names" %>

Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols

' To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
' <System.Web.Script.Services.ScriptService()> _
<WebService(Namespace := "http://tempuri.org/")> _
<WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _  
Public Class Names
    Inherits System.Web.Services.WebService
   
    <WebMethod()> _
    Public Function Names(ByVal prefixText As String, ByVal count As Integer) As String()
        Dim list As New List(Of String)
        For i = 1 To 5
            list.Add(prefixText & " - " & i)
        Next
        Return list.ToArray
    End Function
End Class

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Search.aspx:
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...
Test: <asp:TextBox ID="TEST" runat="server" />

 <cc1:AutoCompleteExtender runat="server" ID="autoComplete1" TargetControlID="TEST" ServiceMethod="Names" ServicePath="Autocomplete.asmx" MinimumPrefixLength="2" CompletionInterval="1000" EnableCaching="true" CompletionSetCount="20" DelimiterCharacters=";, :" ShowOnlyCurrentWordInCompletionListItem="true"></cc1:AutoCompleteExtender>
...

Thanks in advance for any assistance you can offer!