Great. Thank you.
Alessandro - on StackOverflow:
You have to migrate your existing content with old workflow to the new one.
In the ZMI portal_workflow for the Document type must be specified the OLD workflow.
Then go to the Plone control panel -> Types (@@types-controlpanel) -> choose Document in the drop down menu and then choose the new workflow.
Now you are able to properly configure exact match between old states and the new ones.
Click apply to start migration.