Transfer data from Sql Server 2005 to Adobe Flex 2.0 as xml

Why is Adobe Flex 2.o  giving me the error "The markup in the document precending the root element must be well-formed" when trying to load xml via an .aspx script produced string, yet it works if I save the string as a .xml?

I am calling the script in Flex as such

<mx:XML id="treeData" source="bin\xml\user_list.aspx" />

THis is my .aspx
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<?xml version="1.0" encoding="iso-8859-1"?>
<%@ Page Language="VB" Debug="true" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.IO" %>
<%@ Import Namespace="System.Web" %>
<%

Response.Cache.SetExpires(DateTime.Now.AddSeconds(1))


Dim ConnString as String  = "-------------------------------------"


'      get users from database
Dim userConn As New SqlConnection( ConnString )
userConn.Open()

Dim userSQL as String = "SELECT * FROM userAccounts ORDER by last_name ASC;"
Dim userCommand As New SqlCommand(userSQL, userConn)
Dim userDataReader As SqlDataReader = userCommand.ExecuteReader


Dim dataOutPut as String = ""                                                    

dataOutPut += "<nodeTop>"

While userDataReader.Read()   '      read move count forward by one, returns false if next one does not exist
'WHILE  groupCount < 10

            dataOutPut += "<node label='" & userDataReader("user_name") & "'>"
          dataOutPut += "<node user_name='" & userDataReader("user_name") & "'/>"
                  
            dataOutPut += "</node>"
      

End While

userDataReader.Close()
userConn.Close()

dataOutPut += "</nodeTop>"

response.write(dataOutPut)

%>

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I really just need to know the best way to share data between Flex and SQL Server without resorting to web or data services.  I want to do it strickly through scripts or if sql server has something better im all ears.  Thanks