Converting Purchase Requisition to Purchase Order

Hello all.

My scenary:

Product X: Where the Purchase Requisition was created.

Product Y: Product where the requirement of product X was created. Here we have 2 PlannedOrders. But the date of these PlnOrd are 03.28.2011(Past mm/dd/yyyy).

The Problem: GATP shows the date of Purchase Order based on Product Y(03.28.2011). Every time we have avaliable stock, SCM accepts dates in past.

How i can solve this? I need SCM never shows past dates.

Thanks and best regards.