Excel export is not working / Access denied for Excel application - IIS Excel access issue

This is a COM permissions problem.

1. Start > Run > dcomcnfg (or “mmc -32” and then add the Component Services snap-in manually if you can’t find the app under step 3)
2. Navigate to Component Services > Computers > My Computer > DCOM Config
3. Locate the MS application giving you trouble (eg: “Microsoft Excel Application” for Excel or “Microsoft Word 97 – 2003 Document” for Word)
4. Right click > Properties
5. On the security tab: Select Customize under Launch and Activation Permissions / Access Permissions and click Edit…
6. Add the account under which the site is running (eg: Network Service) and assign Local Launch & Local Activation permissions