Windows server 2003

When i try to connect a service from my windows 2003 server, it gives below error:

12029 - Unknown error.

From internet i can find that 12029 - A connection could not be established to the server.

The legacy code is written in VB6.

code: 

objXmlHttp.open "POST", modRegistry.GetString(HKEY_LOCAL_MACHINE, "SOFTWARE\TMS\DPMS\TOMS", "WSURL"), False
objXmlHttp.setRequestHeader "Content-Type", "application/x-www-form-urlencoded"
objXmlHttp.setRequestHeader "Authorization", modRegistry.GetString(HKEY_LOCAL_MACHINE, "SOFTWARE\TMS\DPMS\TOMS", "Authorization")
mfurlxml = "FUNCTION=VALIDATE&DATA=" & URLEncode(objDom.xml)
'objXmlHttp.send "FUNCTION=VALIDATE&DATA=" & URLEncode(objDom.xml)
objXmlHttp.send (mfurlxml)

I have tried all the below ways to make it work. Still my request does not reaches the server. Can anyone please help me?

1. Changed the default Web site to use (All Unassigned) IP addresses

2. Cleared firewall issue

3. Unchecked all three boxes under Internet options->connections->lan settings