Wotlk downloaded from other server cant change realmlist?

I downloaded the the wotlk 3.3.5a from another server cuz here i was having problem to download it does it matters?
And i cant change the realmlist it says: you dont have permission to do that...

help pls

Before you change the file
1. Make sure that the file is either NOT in C drive, or that you are logged in an admin account
2. Make sure the file is not read-only