HTTPrequest problem

[Trav-Pro]

This is a raw data of a website ( Got it using fiddler )

HTTP/1.1 200 OK
Date: Thu, 26 Aug 2010 00:30:34 GMT
Server: Apache
X-Powered-By: PHP/5.2.9
Vary: Accept-Encoding
Content-Length: 376
Keep-Alive: timeout=2, max=50
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8

I posted some data using http request on it and got this in return

HTTP/1.1 200 OK
Date: Thu, 26 Aug 2010 01:30:00 GMT
Server: Apache
X-Powered-By: PHP/5.2.9
Vary: Accept-Encoding
Content-Length: 543
Content-Type: text/html; charset=UTF-8

I can't get to post the data with the code below

Dim webRequest As HttpWebRequest
        Dim responseReader As StreamReader
        Dim responseData As String
        Dim postData As String
        Dim part As String() = Label6.Text.ToString.Split(" ")
        postData = "uri=http%3A%2F%2Fxxx.com%2Fxxx%2xxx.php&sender=" & Sms_From.Text & "&sms_to=" & Sms_To.Text & "&sms_text=" & RichTextBox1.Text & "&limit=" & part(2)
        webRequest = TryCast(Net.WebRequest.Create("http://xxxxxxxx/xxx.php"), HttpWebRequest)
        webRequest.Method = "POST"
        webRequest.ContentType = "application/x-www-form-urlencoded"
        webRequest.CookieContainer = cookies
        Dim requestWriter As New StreamWriter(webRequest.GetRequestStream())
        requestWriter.Write(postData)
        requestWriter.Close()
        responseReader = New StreamReader(webRequest.GetResponse().GetResponseStream())
        responseData = responseReader.ReadToEnd()
        responseReader.Close()

So these things are missing in my sent data

Keep-Alive: timeout=2, max=50
Connection: Keep-Alive

I'm not sure what i am doing wrong here , Anyone can help me out ?