cannot call web method from an .aspx page which is integrated in classic asp application.

I am currently working on one application where I have this old application code written in classic asp. For one enhancement requirement I have added an .aspx page in that application (as I prefer asp.net over classic asp). My .aspx page contains some markup and jquery code (some event change code) along with an ajax call to the server side web method. [As a separate solution (asp.net), my .aspx code works perfectly but when I integrate that .aspx page in classic asp application, jquery ajax call to server side web method never reaches. It always throws error. (I have used closures).] Is it really possible which I am trying to achieve? If yes, HOW? Or what could be the cause of error? I have also tried removing the ajax code segment from .aspx and tried writing the same event change code at server side.. DOESN'T WORK either. Any suggestions would be appreciated. Thanks in advance!