File Upload in Silverlight

 Hey out there.

 I turned my relevant projects in my solution to static portnumbers... I just have a problem with the above link. My Handler looks like this:

<%@ WebHandler Language="C#" Class="receiver" %>

using System;
using System.Web;
using System.IO;

public class receiver : IHttpHandler {

    public void ProcessRequest(HttpContext context)
    {
        string filename = context.Request.QueryString["filename"].ToString();
        using (FileStream fs = File.Create(context.Server.MapPath("~/" + filename)))
        {
            SaveFile(context.Request.InputStream, fs);
        }
    }

    private void SaveFile(Stream stream, FileStream fs)
    {
        byte[] buffer = new byte[4096];
        int bytesRead;
        while ((bytesRead = stream.Read(buffer, 0, buffer.Length)) != 0)
        {
            fs.Write(buffer, 0, bytesRead);
        }
    }
    
    public bool IsReusable {
        get {
            return false;
        }
    }

}

Yes and my call looks like that:

private string host = "localhost";
private string port = "64670";
private string app = "SensorVisual.Web";
...      
 private void UploadFile_Click(object sender, RoutedEventArgs e)
        {
            // Prompt the user to select an image file.
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Multiselect = false;
            ofd.Filter = "XML File (*.xml)|*.xml";
            
            if ((bool)ofd.ShowDialog())
            {
                string name = "upload" + DateTime.Now.ToString("dd_MM_yy_hhmm") + ".xml";
                UploadFileData(name, ofd.File.OpenRead());
            }
        }
        private void UploadFileData(string fileName, Stream data)
        {
            UriBuilder ub = new UriBuilder("http://"+this.host+":"+this.port+"/"+this.app+"/receiver.ashx");
            ub.Query = string.Format("filename={0}", fileName);

            WebClient c = new WebClient();
            c.OpenWriteCompleted += (sender, e) =>
            {
                PushData(data, e.Result);
                e.Result.Close();
                data.Close();
            };
            c.OpenWriteAsync(ub.Uri);
        }

  But the problem is that it doesn't work. If I start my SL project it works, that I can open http://localhost:64670/SensorVisual.Web/receiver.ashx?filename=test.xml. That works pretty fine, it also creates the test.xml File. My problem is, that it isn't working with this function.

Please could you help me? It's really urgent...

Thanks for your help in advance!

greets