C# Elmah - how to fix when it is working in one website but not another on the same server

I have two copies of the same website on my IIS7.5 windows 2008 server:

Default Website/my_app
Beta/my_app

The code base for the two are identical,开发者_运维百科 and they both have identical web.config files.

On the default website, ELMAH works and logs messages (to file), but on the Beta website it does not log anything. What can I check to see why it is not working?

I have compared the ACLs for both physical folders and they are the same.

All it need is a write permission for apppool identity.
We are using very simple webdeploy package for automagic managing ACLs.
You should check ACLs for appPools
I'm sure your site use different identities.