The most likely reason your code does not work is that you are using the registration code when you should be using the attendance code. Read this brief description to understand the difference between the codes.
There are two types of codes - a registration code and the attendance code. The instructor sends the registration code to your supervisor/team leader, or the coordinator of the event, and they disperse that information to staff. The registration code starts with an "R". The course instructor provides the attendance code at/during the course presentation, and it starts with an "A". Use registration code to register for the event, and you use the attendance code when you are starting the process to complete the evaluation to obtain your certificate.
If you are using the right type of code at the right time and it still does not work, please contact the person who gave you the code to verify the numbers. The registration and attendance codes are unique to each event.