Account assignment in purchase requisition: mandatory fields

Hello gurus:

We have set sales order as mandatory for a certain account assignment category.

It works fine for the purchase order, so that you can't save the item without indicating the sales order in the account assignments.

But on ME51N(or ME52N), the check doesn't work the same way: even though the purchase requisition has a sales order on its account assignment, systems sends error message ME083, prompting the user to put a sales order (which is not posible, as the purchase requisition already has one).

I would say that this is not a consistent behavior of the account assignment check, but haven't found any note about this issue and none of the discussions I have looked at address this matter.

I wonder if any of you has ever experienced something like this.

Thanks in advance for your help.

Best regards.

David Ramos.

PORCELANOSA MM.