Webservice call from VB6 code results in "Request format is invalid " System error

Here is my code

Private Sub PassTXrecordtoGP(ByVal sopNum As String, ByVal WOnum As String, ByVal mustNumb As String)
Dim objXMLHTTP As MSXML2.XMLHTTP60
Dim sURL As String
Dim i As Integer

i = 1
For i = 1 To 3

If (Len("" & sopNum) = 0) Or (Len("" & WOnum) = 0) Or (Len("" & mustNumb) = 0) Then Exit For
sURL = "http://192.168.214.111/webservice/integration.asmx/PreauthMode2?WOnum=" & WOnum & "&masterNumber=" & mustNumb & "&invoiceNumber=" & sopNum
Set objXMLHTTP = New MSXML2.XMLHTTP60
objXMLHTTP.Open "POST", sURL, False

objXMLHTTP.Send

If InStr(1, objXMLHTTP.responceText, "success") > 0 Then   'webserv开发者_高级运维ice call is successful, No need to try 3 more times!
    Set objXMLHTTP = Nothing
    Exit For
Else
    Set objXMLHTTP = Nothing
    GoToSleep 2     'wait for 2 seconds and then retry again!
End If

Here is an error:

System.InvalidOperationException: Request format is invalid: .
at System.Web.Services.Protocols.HttpServerProtocol.ReadParameters()
at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()
status = 500: "Internal Server Error"

What am i doing wrong? Thanks for help everyone.

Sounds like it is a problem with the Server side. Either you have the wrong address, or the server does not know how to respond to your request because you are sending invalid parameters.

Try a 'Get' Instead of a 'Post' since you are sending your parameters through a querystring.

http://www.checkupdown.com/status/E500.html