Lists ASMX sharepoint web service

Hi all, I'm trying to connect to the sharepoint web service and output the data of a list, if I use GetList it seems to retrieve some info ok. but when trying to use GetListItems to output the data of a list I get blank data. My code is as follows:

<script runat="server">

 private void button1_Click(object sender, EventArgs e) {

 // Display the greeting label text.
GreetingLabel.Visible = true;

string listGUID = "xxxxx-xxx-xxx-xxxx-xxxx";

StringBuilder sbEnvelope = new StringBuilder(); sbEnvelope.Append("<?xml version=\"1.0\" encoding=\"utf-8\"?>"); sbEnvelope.Append("<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" " + "xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" " + "xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">"); sbEnvelope.Append(string.Format( "<soap:Body>" + "<GetListItems xmlns=\"http://schemas.microsoft.com/sharepoint/soap/\">" + "<listName>Student Handbook</listName>" + "<viewName></viewName>" + "<viewFields><ViewFields xmlns=''><FieldRef Name='Chapter' /><FieldRef Name='Section Title'/></ViewFields></viewFields>" + "<rowLimit>100</rowLimit>" + "</GetListItems>" + "</soap:Body>", listGUID)); sbEnvelope.Append("</soap:Envelope>");    try {

HttpWebRequest req = (HttpWebRequest)WebRequest.Create("https://server/_vti_bin/Lists.asmx");

req.Method = "POST"; req.ContentType = "text/xml; charset=\"utf-8\""; req.Accept = "text/xml"; req.Headers.Add("SOAPAction", "\"http://schemas.microsoft.com/sharepoint/soap/GetListItems\""); req.UseDefaultCredentials = true;   using (Stream stream = req.GetRequestStream()) { using (StreamWriter writer = new StreamWriter(stream)) {

writer.Write(sbEnvelope.ToString());

} }

WebResponse response = req.GetResponse(); Stream responseStream = response.GetResponseStream();   XmlDocument xDoc = new XmlDocument(); xDoc.Load(responseStream); XPathNavigator xNav = xDoc.CreateNavigator(); GreetingLabel.Text += xNav.OuterXml.ToString(); } catch (Exception ex) { GreetingLabel.Text = sbEnvelope.ToString() + "\r\n----\r\n" + ex.ToString(); } }

</script>

can anybody help?! thanks