Automatic Grade Change

Hi,

While changing the organisation that an employee belongs to using the self service functions, if an employee's grade is not a valid grade (not in the list of valid grades for the job profile the employee is in), then the grade is automatically changed to the default grade against the current job profile.

We changed this behaviour by setting the profile option HR:Use Grade Defaults to No. However, now when we change the  job profile, the grade does not change to a valid grade.

First question, why does the grade change when organisation is being changed for an employee?