Melvyn, just because it is "unlocked" does not mean you have root access. It just means the bootloader is unlocked.
Now the big question here is CAN YOU GET TO RECOVERY???
And a related one is, DO YOU HAVE SUPERUSER.
When you use a root app(like ROM Manager) does ask you to allow superuser access to the app? Also you can DL terminal Emulator and open it and type SU and then see if the $ prompt turns to a # prompt.
If you have SU access but cannot get to recovery see thread here....