Sales Areaof S.O. should be match with S.A. Customer Master

Dear Experts,

I have following requirement,

while creating sales order in the initial screen I have maintained Sales Area (6100,61 & 61) should be match with Sales Area of Customer master what I have maintained(6100,61 & 61) . If I Specified (6100,61 &62) the sales area of Sales Order mismatch with Sales Area of Customer Master that time system should give the error massage. Sales Order should not proceed. How can I configure the system so that system should give the error massage.

Regards,

Manzoor Ahmad