Are you logged in with Admin rights?
Generally the folders on a mac are created with 'full' read-write capabilities for the particular user who installed it (whomever is logged in atm) and 'limited' rights to any other users.
Make sure you're logged in the same account as to when the folder was created.. or if you have admin rights, change the Ownership & Permissions.
- Highlight the override folder and Apple+I (or "Get Info").
- scroll to the bottom of the window and click the "Details" arrow under Ownership & Permissions
- Check that each pulldown window states "Read & Write".
- Click the "Apply to enclosed items" button.
If you have Admin rights.. that should do the trick