SESSION TIME OUT ISSUE

My doubt is on a classic asp application. The session time we have set up on the IIS is not being considered and it kicks out the customers very frequently from the application which creates a huge problem.  We dont have have the session time out set up anywhere in the code and I believe IIS set up should work through the webconfig file. Not sure where else this could have been set up.

We had this working fine till few days back before we did a huge  DB change. Previously we had 10 database and we planned to merge it all to one. So we created a new instance  with merged database and moved to this instance. We have not changed anything on the code except for the connection strings but we are not getting a solution on this time out issue.

We have changed the session time out to 40 minutes in the application pool in IIS and restarted the IIS for the changes to get affected. But it does not work. Please provide us your valuable solution.  Most part of our application is in classic asp where few are asp.net applications which we have created as separate application and  integrated with the asp application.