Debian – How to preconfigure package using debconf-set-selections

I am trying to preconfigure redmine instalation and I have got stuck with

debconf-set-selections pkg.selections

Resulting in lot of error messages

error: Cannot find a question for redmine/instances/default/password-confirm
error: Cannot find a question for redmine/instances/default/pgsql/admin-pass
error: Cannot find a question for redmine/instances/default/mysql/admin-pass
error: Cannot find a question for redmine/instances/default/app-password-confirm
error: Cannot find a question for redmine/instances/default/mysql/app-pass
error: Cannot find a question for redmine/instances/default/pgsql/app-pass
error: Cannot find a question for redmine/instances/default/db/app-user
error: Cannot find a question for redmine/instances/default/default-language
error: Cannot find a question for redmine/instances/default/remote/newhost
error: Cannot find a question for redmine/instances/default/db/basepath
error: Cannot find a question for redmine/instances/default/upgrade-error
error: Cannot find a question for redmine/instances/default/pgsql/changeconf
error: Cannot find a question for redmine/instances/default/missing-db-package-error
error: Cannot find a question for redmine/instances/default/db/dbname
error: Cannot find a question for redmine/instances/default/purge
error: Cannot find a question for redmine/instances/default/remote/host
error: Cannot find a question for redmine/instances/default/dbconfig-upgrade
error: Cannot find a question for redmine/instances/default/internal/reconfiguring
error: Cannot find a question for redmine/instances/default/upgrade-backup
error: Cannot find a question for redmine/instances/default/pgsql/method
error: Cannot find a question for redmine/instances/default/install-error
error: Cannot find a question for redmine/instances/default/mysql/admin-user
error: Cannot find a question for redmine/instances/default/database-type
error: Cannot find a question for redmine/instances/default/pgsql/manualconf
error: Cannot find a question for redmine/instances/default/pgsql/authmethod-admin
error: Cannot find a question for redmine/instances/default/mysql/method
error: Cannot find a question for redmine/instances/default/internal/skip-preseed
error: Cannot find a question for redmine/instances/default/pgsql/admin-user
error: Cannot find a question for redmine/instances/default/remove-error
error: Cannot find a question for redmine/instances/default/dbconfig-remove
error: Cannot find a question for redmine/instances/default/remote/port
error: Cannot find a question for redmine/instances/default/pgsql/authmethod-user
error: Cannot find a question for redmine/instances/default/dbconfig-install
error: Cannot find a question for redmine/instances/default/dbconfig-reinstall

If I run debconf-set-selections after the package was installed, it works, however, I need to reconfigure the package.

Could someone explain me please the proper way to do this?