Please try to find the reason of your problem with the following steps:
1. Please kindly check whether you could visit https://u1.sothink.com/ using your IE or not(you will see the words "Welcome to Sothink Test Server" if you could visit the above site successfully)?
If you could not see the words, please kindly tell us the error appears.
2. Please make sure you are not using proxy service/setting while registering the program;
3. Please make sure the time difference between your computer's local time and your local time is less than 12 hours.