There are 3 major reasons why this error may be occurring.
1) The computer has been set to Deep Freeze. So any changes that have occurred, including enter a serial number, will be lost after the computer is restarted.
2) The person entering the serial number has not logged in as an administrator and therefore does not have administrative privileges.
3) The person has installed both WordQ and SpeakQ onto the machine. Each has to be registered separately. Often people will put in the WordQ Serial Number and then demo SpeakQ for 30 days. When the second screen appears asking for a second serial number people think that the first serial number didn’t work. In fact the second screen has “SpeakQ” written in tiny print and it’s asking for the SpeakQ serial number, not the WordQ Serial Number. If the person is demoing SpeakQ, then they don’t have to enter a serial number and SpeakQ will expire after 30 days. But WordQ will continue to work beyond that because it’s been registered. If the person wants to register SpeakQ then they can enter the SpeakQ serial number.