Why is differential different for some children?

There are different rates listed when we pay the full time slot for afterschool children within the same center. Why? Ex: Baynes #10013. Some children listed at the $6.60 (see Brian Thompson) and others at $7.10 (see Arnesha Watkins).

RESPONSE
The differential payment is the difference between the daily 'F' and 'S' rates. The younger children have a higher 'F' rate. See if that explains the differences between the differentials.

RESPONSE from KIRSTEN
No. The situation with these children is that they are all school age and that would be the same rate there should not be any difference between them.

RESPONSE from Casey
If the rates file has different 'F' for children of different ages, OneCase is going to pay a different differential rate.