Here is information on how to enable auditing in files and shares
1. Go to Start, Programs, Administrative Tools, Domain Controller Security
2. Now you are in the Default Domain Controller Security Setting.
3. Expand Security SettingsLocal PoliciesAudit Policy.
4. On the right panel, enable the “Audit object access” policy.
5. Run “gpupdate” in a command prompt.
6. Go to the files and folders that you want to audit, right click it and
7. Go to Security tab, click Advanced, go to Auditing Tab.
8. Check the two boxes under Add and then click Add.
9. Enter the object name in the blank, and click OK.
10. Test whether it works now.