Delivery related issue

Hi all

I am a SD consultant plz guide me on ds issue

I have enough stock ,let say 1000 , when i am creating a sales order for 10 quantity it is confirmed during d availablity chk and gives the delivery date as wel.

But when i am creating a delivery on the desired date it shows quantity 0 (zero) is available. neither the quantity is copied from the order to delivery

I am using standard material p-100

What would be the posible reason

Thank you