Web authentication

[xor83]

I am trying to login to a web site using Winsock but i am not able to get any response from the site
this is the code i am using to login

Private Sub cmdLogin_Click()
Call DisableAll
lblStatus.Caption = "Logging In..."
Winsock1.RemoteHost = "test.authorize.net"
Winsock1.RemotePort = 443
Winsock1.Connect
End Sub
Private Sub Form_Initialize()
   InitCommonControls
End Sub
Private Sub Winsock1_Connect()
PostData = "MerchantLogin=Test&Password=Test"
   Winsock1.SendData "POST" & " /ui/themes/anet/Logon.aspx?sub=signin HTTP/1.1" & vbCrLf & _
       "Host: test.authorize.net" & vbCrLf & _
       "User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13" & vbCrLf & _
       "Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5" & vbCrLf & _
       "Accept-Language: en-us,en;q=0.5" & vbCrLf & _
       "Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7" & vbCrLf & _
       "Accept - Encoding: gzip , deflate" & vbCrLf & _
       "Keep-Alive: 300" & vbCrLf & _
       "Connection: keep-alive" & vbCrLf & _
       "Referer: https://test.authorize.net/ui/themes/anet/Logon.aspx?sub=signinMerchantLogin=Test&Password=Test" & vbCrLf & _
       "Content-type: application/x-www-form-urlencoded" & vbCrLf & _
       "Content-Type: application/x-www-form-urlencoded" & vbCrLf & _
       "Content-Length: " & Len(PostData)
PageSource = vbNullString
End Sub

but i don't get anything in Winsock1_DataArrival it just do nothing after successfully login to site

i have also tested on other login site it work fine

this is the info i get from Firefox Addon

https://test.authorize.net/ui/themes/anet/Logon.aspx?sub=signin

POST /ui/themes/anet/Logon.aspx?sub=signin HTTP/1.1
Host: test.authorize.net
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.13) Gecko/20080311 Firefox/2.0.0.13
Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: https://test.authorize.net/ui/themes/anet/logon.aspx
Cookie: stoken=_QoCnESBalNW6cHDwUT%24BB8bcTmvtOcHMY%24b9%24aAcGQA; rwizard=6
Content-Type: application/x-www-form-urlencoded
Content-Length: 32
MerchantLogin=Test&Password=Test
HTTP/1.x 200 OK
Server: Microsoft-IIS/5.0
Date: Wed, 02 Apr 2008 13:54:17 GMT
X-Powered-By: ASP.NET
X-AspNet-Version: 1.1.4322
Cache-Control: private
Content-Type: text/html; charset=utf-8
Content-Length: 8813

can anybody tell me how can i login using this info?