Rails Backup: Generating Backup Model not running with dokku

Using Backup gem to do a DB backup, deployed the app with the gem installed to DigitalOcean and the next step is to run the generator using

dokku run oktob bundle exec backup generate:model --trigger oktob_db_backup --databases="postgresql" --storages="dropbox" --encryptors="openssl" --compressors="gzip" --notifiers="mail"

this should create the configuration files to setup the backup, but it returns nothing.

When I run the generator on my local machine, 2 files are generated as normal as but this time without using dokku run oktob as it's on a local machine.

Generated model file: '/Users/ahmadajmi/Backup/models/oktob_db_backup.rb'.
Generated configuration file: '/Users/ahmadajmi/Backup/config.rb'.

Thanks