I've been building an Odoo 9.1 module with this (https://www.odoo.com/documentation/9.0/howtos/backend.html#workflows) tutorial. The ad-hoc Session workflow was working fine. But when I implemented the Server Actions, the workflow stopped working (When I click on the Confirm button, nothing happens, no error log etc). What should I do? 

(If you don't have enough karma to answer, here's the SO link: https://stackoverflow.com/questions/46108003/a-workflow-with-server-action-is-not-working-on-odoo-9-1)