There are three Carbonite addons in the package.
Make sure that there are directories called "Carbonite", "CaboniteNodes" and "CarboniteTransfer" in the Interface/AddOns directory.
It's possible that your directory structure looks like this:
Interface
| - AddOns
| - | - Carbonite
| - | - | - Carbonite
| - | - | - CarboniteNodes
| - | - | - CarboniteTransfer
which is incorrect.
Check the
FAQ for more details.
Also, make sure you have the most recent version of Carbonite (3.100), make sure all three are enabled in the AddOns list at the character select screen, and make sure that "Load Out of Date" is ticked.