windows phone 7 - parse xml return after a post method -

i use post post parameter server , result in string, how parse result , bind listbox? seems (for reason) can't output string textblock or messagebox. parse xml use xdocument (which take stream in parameter) code following:

    private static void getrequeststreamcallback(iasyncresult asynchronousresult)     {         string post = "track=love"; //       post = httputility.urlencode(post);         console.writeline(post);         try         {             httpwebrequest request = (httpwebrequest)asynchronousresult.asyncstate;              // end operation             stream poststream = request.endgetrequeststream(asynchronousresult);              // convert string byte array.             byte[] postbytes = encoding.utf8.getbytes(post);              // write request stream.             poststream.write(postbytes, 0, postbytes.length);             poststream.close();              // start asynchronous operation response             request.begingetresponse(new asynccallback(getresponsecallback), request);         }         catch (exception ex)         {             messagebox.show(ex.tostring());         }     }      private static void getresponsecallback(iasyncresult asynchronousresult)     {               httpwebrequest request = (httpwebrequest)asynchronousresult.asyncstate;              // end operation             httpwebresponse response = (httpwebresponse)request.endgetresponse(asynchronousresult);              httpstatuscode rcode = response.statuscode;             stream streamresponse = response.getresponsestream();              streamreader streamread = new streamreader(streamresponse);          //this return "" value, expect return xml string                            string str = streamread.readtoend();              //console.writeline(responsestring);             // close stream object             streamresponse.close();             streamread.close();             // release httpwebresponse             response.close();                  } 

and want use xdocument parse data this:

 xdocument xdoc = xdocument.load(str);                      var data = query in xdoc.descendants("tracks").elements("item")                                select new searchresult                                {                                    artist = (string)query.element("artist"),                                    album = (string)query.element("album"),                                    track = (string)query.element("track"),                               //   artista = (string)query.element("artists").element("artist"),                                };                     listbox1.itemssource = data;                      var data1 = query in xdoc.descendants("artists").elements("item")                                select new searchresult                                {                                  artista = (string)query.element("artist"),                                };                     listbox2.itemssource = data1;