AutoCreate Purchase Order

Dear Experts,

User has booked on Purchase Requisition with 10 different items. The price for each item is generated through Supplier Quotation. All lines has preference to a particular one supplier.In other words one purchase request for 10 item against a single supplier was booked and approved. The AutoCreate has generated three purchase orders.

User expect to get one Purchase Order against approved Purchase Requisition which has different lines but all these lines requesting from single supplier where needby date is same.

What could be wrong with setup which has generated separate POs. Please guide me.

Thanking you.

Ismail