Thanks for your reply. Using a sharepoint service and donot have access
to the webservice class. Modified the .disco and .wsdl files to support
service virtualization. Could that be a cause for it? Posting my asmx,
disco and wsdl files if that could help.

Thnaks mate,

-Rohit

My search.asmx reads as follows:

<%@ WebService Language="c#"
Class="Microsoft.Office.Server.Search.Query.QueryService,
Microsoft.Office.Server.Search, Version=12.0.0.0, Culture=neutral,
PublicKeyToken=71e9bce111e9429c" %>

Changed the searchdisco.aspx to :

<%@ Page Language="C#" Inherits="System.Web.UI.Page"   %> <%@ Assembly
Name="Microsoft.SharePoint, Version=12.0.0.0, Culture=neutral,
PublicKeyToken=71e9bce111e9429c" %> <%@ Import
Namespace="Microsoft.SharePoint.Utilities" %> <%@ Import
Namespace="Microsoft.SharePoint" %>
<% Response.ContentType = "text/xml"; %>
<discovery xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://schemas.xmlsoap.org/disco/">
 <contractRef ref=<% SPEncode.WriteHtmlEncodeWithQuote(Response,
SPWeb.OriginalBaseUrl(Request) + "?wsdl", '"'); %> docRef=<%
SPEncode.WriteHtmlEncodeWithQuote(Response,
SPWeb.OriginalBaseUrl(Request), '"'); %>
xmlns="http://schemas.xmlsoap.org/disco/scl/" />
 <soap address=<% SPEncode.WriteHtmlEncodeWithQuote(Response,
SPWeb.OriginalBaseUrl(Request), '"'); %>
xmlns:q1="http://microsoft.com/webservices/SharePointPortalServer/WebQueryService"
binding="q1:QueryServiceSoap"
xmlns="http://schemas.xmlsoap.org/disco/soap/" />
</discovery>

And also changed the searchwsdl.aspx service definition to :

<service name="QueryService">
   <documentation>SharePointPortalServer Query service</documentation>
   <port name="QueryServiceSoap" binding="s1:QueryServiceSoap">
     <soap:address location=<%
SPEncode.WriteHtmlEncodeWithQuote(Response,
SPWeb.OriginalBaseUrl(Request), '"'); %> />
   </port>
 </service>