Rebate relevant setting

Hello SAP Experts,

There is a one Billing document created in sales area, 3500 /50/ 20.

Customer Master record maintained in 3500 / 50/20 has rebate flag ACTIVATED, whereas record maintained in 3500 /50 /30 has it DEACTIVATED.

This document should Ideally  consider the Rebate Relevant flag of Customer master record in 3500 / 50 /20 ,but instead it is considering

the Customer master record maintained in 3500 / 50 / 30.

Could you let me know, is there some dependency of Rebate relevant flag maintained in one sales ares on another sales area ??

Thanks in advance your answer.

Thanks and Regards,

Umesh  Karane.