Visual Studio .NET - Accessing Web Client

hi iam using asp.net try to accsess webclient 

     Dim url As String = String.Empty
       url = "https://www.liveMeeting.com/cc/lmtrial2005/xml/4.0/GetPostingURLRequest"
       

        Try
            Dim wc As WebClient = New WebClient
            Dim output As Byte() = wc.DownloadData(url)
            Response.Write(System.Text.Encoding.UTF8.GetString(output, 0, output.Length))
        Catch ex As Exception
            Response.Write(ex.ToString())
        End Try



Iam getting the following Exception 

System.Net.WebException: The underlying connection was closed: 
Unable to connect to the remote server. at System.Net.HttpWebRequest.CheckFinalStatus() 
at System.Net.HttpWebRequest.EndGetResponse(IAsyncResult asyncResult) 
at System.Net.HttpWebRequest.GetResponse() 
at System.Net.WebClient.DownloadData(String address) 
at TestDemo.WebForm1.Button2_Click(Object sender, EventArgs e) 
in c:\inetpub\wwwroot\TestDemo\WebForm1.aspx.vb:line 133 

do i have to set any special  permission ? or need to set any configruation.
iam unlucky in my google search.

Pls Help

Asp.net requires Proxy information to process the request.


       Try
            Dim d1 As System.Net.WebProxy
            d1 = New System.Net.WebProxy("172.16.1.100", 3128)
            Dim lcUrl As String = "https://www.liveMeeting.com/cc/lmtrial2005/xml/4.0/GetPostingURLRequest"
            Dim loHttp As HttpWebRequest = CType(WebRequest.Create(lcUrl), HttpWebRequest)
            loHttp.Proxy = d1
            loHttp.Method = "GET"

            Dim loWebResponse As HttpWebResponse = CType(loHttp.GetResponse, HttpWebResponse)

            Dim enc As Encoding = System.Text.Encoding.GetEncoding(1252)

            Dim loResponseStream As StreamReader = New StreamReader(loWebResponse.GetResponseStream, enc)

            Dim lcHtml As String = loResponseStream.ReadToEnd

            loWebResponse.Close()

            loResponseStream.Close()
        Catch ex As Exception
            Response.Write(ex.ToString())
        End Try



 d1 = New System.Net.WebProxy("172.16.1.100", 3128)

172.16.1.100 = Proxy Server
3128 - Port.

thats all it works fine