my sales total is not balancing after deleting some invoices. for instance, i made 4 invoice that totaled to $500 and add 2 new invoices again of $300 to totally sum $800. for some reasons i deleted the new added 2 invoices that i expect my total to be back to $500. but quite odd, still found my total to be $800. i don't understand why. i need ways to set my system to allow deleted invoice to reduce my total value as illustrated above.