Multiple IIS worker process issue with ajax

See more:

IIS

Ajax

IIS7.5

ASP.NET4

Here is the scenario:

I am using a asp.net web application with ASPX pages. In one of the Web Page I have written couple of Web Methods and are calling them from AJAX. Now this works fine when the worker process of the application pool is set to 1 but as soon as a Web Garden is created it throws the dreaded '500' exception. Any help will be really appreciated.

What I have tried:

My Web Methods Looks something like this:

[System.Web.Services.WebMethod(EnableSession =true)]
public static ListDisbursementStatus FindResult(string userId ,string disbursementDate, string currentPageNo = "1")
{
.....
}

From Ajax I am calling this method:

$.ajax({
url: "<pagename>.aspx/FindResult",
type: "POST",
........
});