Michael,
Like Bernhard said u need to do a system trace to identify missing authorization Authorization check
- Go to ST01 and check "Authorization Check"
- Turn on "Trace On" and ask the user to navigate where he is missing the access
- Once the finished with error for missing authorization Turn off trace
- Analysis the trace record by username which will help you to get missing authorizations
Hope it will be helpful for you.
Regards,
RK