Hi Thu
If you still face the issue I think it will help finding the issue if you will upload additional screenshots:
1. The form where you get the error including data used
2. Sales tax group configuration (sales tax group used in the form where you get the error)
2. Item sales tax group configuration (item sales tax group used in the form where you get the information
3. Sales tax code that the used sales tax group and item sales tax group have in common)
4. General ledger parameter - fast tab Sales tax
Kind regards
Sten
PS. The account structure used, have they been activated after the sales tax accounts have been added the account structures?