Srini,

I had that error at one point and I am not sure how I cleared it up. I
would check that you have the right data types in the envelope XML for
the parameters that are being passed.  WhatI did too was write
information to the event log from the Web Service so I at least had an
idea of where it was failing and if it was even running part way
through.

The only way we were able to call a .Net Web Service from an Oracle
PL/SQL function or procedure, using HTTP 1.1  was:

- Add the following to Web.config:
  <webServices>
        <protocols>
        <add name="HttpPost"></add>
        <add name="HttpGet"></add>
     </protocols>
  HTTPSoap is the default.  This allows Get and Put requests to your
Web service rather tahn using Soap.  The danger here is you open to
attacks such as denial of service since the Web Service now processes
Gets and Posts.

- Instead of using Soap to call the web service, you need to call it
like a regular web page:
    tmpVar :=
utl_http.request('http://www.something.com/mydir/service1.asmx/HelloWorld?parm='

- You need to sift through the return value (tmpVar in this case) to
find the actual return in the XML string returned

This only pertains if you are using a HTTP/1.1 protocol.  If using 1.0
the regular SOAP method should work.

Hope this helps.

John