This is the SQL syntax I have:
SELECT ReceiptsData.*, DCount("[InvoiceNumber]","sub_InvoiceLineItems","[InvoiceDate]<=#" & [InvoiceDate] & "#") AS LineItemNumber
FROM ReceiptsData
ORDER BY DCount("[InvoiceNumber]","sub_InvoiceLineItems","[InvoiceDate]<=#" & [InvoiceDate] & "#");
This gives...