But there are multiple Quantities... You can't get a single quantity by looking up the ProductID(column) in ProductBatch (Table) ?!
Should they be added together? The first one used? The last one? What do you do if there is more than one row? What is the recordset used for?
As I suggested earlier, this may be too complex to handle in this forum and a premium support ticket might be appropriate so I can get a better picture of what exactly you are doing and how it works in context of the rest of your site.