I did use group by... I made this query last year and there were no issues, till yesterday.
SELECT InvoiceFinalMain.CompanyName, InvoiceFinalMain.InvoiceNum, InvoiceFinalMain.Invdate, InvoiceFinalSUB.Product, InvoiceFinalSUB.Particulars, InvoiceFinalSUB.Amount, FinalTotalBill.TotalBill...