Does not work?

Funny that no one so far noted this...
I tried revisions_fu on node type book as well as on node type page after a colleague firmly reported that this module "doesn't work". Sadly have to confirm: behaviour at conflicting resp. simultaneous edits is just like without this module.
As far as I can see there are no dedicated permissions for this module. What else might I have done wrong? (In the latter case change the issue component to "user interface" and please add lacking information)