I had a similar issue where there were no invoices shown when the customer did a lookup of open invoices. We had to replace the lookup files. In Windows Explorer, go to ..\Mas90\Soa. Rename SY1Q01, SY1Q02, SY1Q03, SY1Q04, and SY1QDD. Replace with backup or I've seen people take them off their personal support machine. Just be sure you backup, etc.