There could be a few reasons;
1- You directed your family and friends to sign up at well.burnalong.com/register, rather than sent the a link to register their free subaccount via your account. (See article "how to add a subaccount.")
2- They used a different email address as their username then the one you sent the email invite into.
*For both of these situations, please email email@example.com so that we may deactivate their current account.
3- They have email domains such as Yahoo or Aol that is blocking the Burnalong email domain. In that case, please reach out to firstname.lastname@example.org
so that we may send you to link that is being blocked from coming through.