Unable to write data to transport connection

[uttara]

Hello All,
I get this message when I am trying to post data to some site. I don't
get the same message from this other site I have my application running on.
Dim req As System.Net.WebRequest =
System.Net.WebRequest.Create("http://someurl.aspx")
req.Method = "POST"
req.Timeout = 900000
req.ContentType = "application/x-www-form-urlencoded"
Dim bytedata As Byte() =
System.Text.Encoding.UTF8.GetBytes(xmlFile)
req.ContentLength = bytedata.Length
Dim RequestStream As stream = req.GetRequestStream()
RequestStream.Write(bytedata, 0, bytedata.Length)
RequestStream.Close()

Dim stream As StreamReader = New
StreamReader(req.GetResponse().GetResponseStream() )
Dim webresponse As HttpWebResponse =
CType(req.GetResponse(), HttpWebResponse)