I tried by accessing an invalid page. In the error log I can see the entry for page not found. But, errror response shown to the user is not the page I configured in the obj.conf. Instead it is displaying the default browser error page for 404 error. Please let me know what could be wrong.
It might be a late response but the reason you see Browser's default 404 page is IE has a check for 404 page and if this new error page you configured is less that 512 bytes IE will display its own default 404 page.
The solution for your problem is to have your custom page to be bigger than 512 bytes.