Account in PO

Different between PO with account category Q with valuated stocj project and not valuated stock project.

The account in PO that have the element WBS with valuated stock is carried out from T030 By valuation class of material....when I make a Po with an elemet WBS that haven't a stock valuated the account is not carried out from T030 but it is possible insert it by manually.That i write is it OK?

Thank you