Lot size procedure

Dear Gurus,

I am having a sales order for quantity 10 items and my scenario is MTO (20). Due to my production constrains... I can go for the production for 1 piece only. At a time I can not produce more than one item. So my MRP run should create individual planned orders (of quantity 1) for the total Sales order quantity. I tried with fixed lot sizing (lot size = 1). But still system is creating planned order for 10 items. What could be problem???

Regards.