That command is incorrect for backing up/exporting the RAP whitelist. The whitelist is part of the local-user db. Use the following command (it will export the entire user db; not just the RAPs)
local-userdb export <name of file>
You'll need to load the file onto the new controller's flash (TFTP, etc.).
local-userdb import <name of file>
The import/export can also be done in the Web UI through the Internal DB server definition.