<sigh> In section 11 in the tutorial it states...
"11.Copy the following snippet of code (Ctrl or Cmd + C):
- (SELECT Coalesce(SUM(DetailQuantity),0) FROM orders Inner Join orderdetails ON orderdetails.DetailOrderID = orders.OrderID WHERE OrderDate > ProductUpdateDate AND DetailProductID = ProductID) AS RemainingInventory
12. Paste the snippet into the Recordset (Ctrl or Cmd + P) :"
What the tutorial fails to mention is that the "-" symbol is being used to do a calculation using the stock field in the database so you MUST place this snippet immediately after the stock field in your recordset.
Easy when you know how - bloody difficult to fathom when you don't.