I have found that sometimes the AFP on or off status in the menu is not always correct. I WILL always turn on AFP for a folder but sometimes the status still says it is off. I realize that maybe the could be caused by manual editing of the conf file afterwards, but if I'm not mistaken I think it has also happened without user interference!
Try to enable one folder. Then disable it. Then enable a different folder. Then re-enable the first.
Try to enable one folder. Then disable it. Then enable a different folder. Then re-enable the first.