How can you be rebels in rome total war

1. Go to My Computer.
2. Click on Disk Drive C.
3. Click on Program Files.
4. Click on The Creative Assembly.
5. Click on Rome - Total War.
6. Click on data.
7. Click on descr_sm_factions.
8. Find the section for slave.
9. Find custom_battle_availability and replace no with yes.
10. Save.

You should (according to most sources) be able to play as the Rebels in Custom Battle. However, I have attempted to do this, but I get the message "Access denied." I someone can figure this out please edit this.