Organizational objects do not create a Business Partner ID

I am setting up SRM org structure with PPOCA_BBP/PPOMA_BBP transaction. I am creating, companies, plants, purchase orgs, purchasing groups and positions and the problem is that SRM is not assigning a Business Partner number to any of those.

I have already checked that there is an internal and external number range setup for Business Partners. Do you have any hints why this could be happening? Your help will be appreciated.

Thank you.