How does system work when running S&OP plan at item category level?

Summary

How does system work when running S&OP plan at item category level?

Content

Dear all,

Please kindly help us to share your knowledge how system works when we run S&OP at item category level.

As I understand, system allows to upload forecast measures at item category level, define bill of resource and souring rule at item category level, since system will use this data to calculate production plan at item category level as well.

However, when I run at item category level, I observed that system did not use the forecast data I uploaded at item category level. System only sum up from item level. It meant that system will sum up all corresponding items which are under appropriate item category.