Custom certificate (plugin)

I am having a problem updating both the Feedback and Certificate modules. When I attempt to update both of these activities (which are the only third party modules I have installed in my Moodle 1.9.7+ site) I get the message "Resource not found". This happens when I try to update the modules from the classroom or directly after creation when I hit the "Update this Feedback" or "Update this Certificate" buttons.

I am getting the same "session key" address in the browser for both modules when I try to update:

course/mod.php?update=717&return=true&sesskey=xjrm8FH7kd

Thanks for any assistance.

Ralph