Struggling - BAQ Last Purchased Job Material

Adam,

What do you mean check the Group By in the sub query but not the calculated field itself?
I also need PODate from POHeader. Would I do this by pulling in another POHeader table or in the subquery itself?
2 subqueries right now total right? PODetail and POHeader? Do I pull them both into the Top query or POHeader into PODetail then PODetail into the Top query with JobMtl?