Anyone seen this when added a Dependent via self-service "Error - Your changes have not been saved b

We are attempting to allow our users to update Retirees using Benefits Self-Service (BSS).  We are already using BSS for active employee benefit enrolment.  When trying to add dependents we are encountering situations where we get the following message: "Error - Your changes have not been saved because the following error occurred : This person does not exist at all or does not exist as of the effective date".  We have not been able to figure out a pattern to it and it does not happen for every dependent being added.  It is interesting to note that we CAN add the dependents using the core forms.  As a result we do have a work around, but it is clumsy to have the users get this error and then have to contact our corporate group (who have core access) to enter the dependent.  Then contact the field to have them complete the benefit enrolment in self-service.