How to add lot number in sales order reservation

Hello

We are on Oracle R12. I am trying to reserve a sales order , next step is to pick release it.

In the sales order line , i go to tools→Scheduling→ Reservation details and on this form i enter the quantity to reserve , there is more than required on hand qty, i did a misc receipt into a specific lot number too. When i click save on the reservation screen, i get an error that Item is lot indivisible , please enter lot information.

My question is where do i enter this lot information? There is no field on the reservation form for lot, and the on hand qty for the item has enough in the lot. So where is this information missing for the form to throw an error.