SubAssistant prevents duplicate substitute accounts from being registered to avoid a number of issues that can occur when duplicate accounts are registered and are being monitored at the same time. If you receive this error, it likely means you've already registered the substitute account on your current SubAssistant account, or you have a different, possibly older, SubAssistant account you used previously that has your substitute account registered with it. If you've used SubAssistant in the past, you should sign in to your original SubAssistant account for each school year; do not create a new SubAssistant account. If you cannot remember if you have another SubAssistant account, use the password reset process to enter email addresses you would have used when you signed up for SubAssistant.
If you don't think you have another SubAssistant account, or you believe the above doesn't apply to your situation, please contact support. When sending your support request, be sure to include the username/user ID of the substitute account you are attempting to register.