If you are getting an error, try these "fixes", in this order, before calling the testing center directly.
Most of the time if you simply close your browser including all open tabs (not using the backspace), and then reopen your browser and log back into RegisterBlast, it may fix the issue. If it does not please try the following:
Make sure your browser is the current version. Some common browsers include Google Chrome, Mozilla Firefox, Microsoft Edge, Opera. NOTE: Safari will not work with Canvas and RB.
Delete your cookies and refresh your browser and try again
Clear your cache and refresh your browser and try again